Registration Statement for Securities to Be Issued in Business Combination Transactions (s-4/a)

As filed with the Securities and Exchange Commission on February 6, 2023
Registration No. 333-268227
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549


AMENDMENT NO. 4 TO FORM S-4
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

NioCorp Developments Ltd.
(Exact name of registrant as specified in its charter)


British Columbia, Canada (State or other jurisdiction of incorporation or organization)		1000 (Primary Standard Industrial Classification Code Number)		98-1262185 (IRS Employer Identification No.)



7000 South Yosemite Street, Suite 115
Centennial, CO 80112
(855) 264-6267
(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)


CT Corporation System
111 Eighth Avenue
13th Floor
New York, New York 10011
(800) 624-0909
(Name, address, including zip code, and telephone number, including area code, of agent for service)


With copies to:

Christopher M. Kelly Joel T. May Andrew C. Thomas Jones Day 1221 Peachtree Street, N.E. Suite 400 Atlanta, Georgia 30361 (404) 581-8967	Bob Wooder Kyle Misewich Blake, Cassels & Graydon LLP 595 Burrard Street Suite 2600 Vancouver, British Columbia V7X 1L3		C. Michael Chitwood Michael A. Civale Skadden, Arps, Slate, Meagher & Flom LLP One Manhattan West New York, NY 10001 Tel: (212) 735-3000		Robert Carelli David Tardif Stikeman Elliott LLP 1155 René-Lévesque West Suite 4100 Montréal, Québec H3B 3V2

Approximate date of commencement of proposed sale of the securities to the public:

As soon as practicable after the effectiveness of this registration statement and upon completion of the transactions described in the enclosed joint proxy statement/prospectus.

If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large Accelerated Filer	☐	Accelerated Filer	☐
Non-Accelerated Filer	☒	Smaller Reporting Company	☒
		Emerging Growth Company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction:

	Exchange Act Rule 13e-4(i) (Cross-Border Issuer Tender Offer)	☐
	Exchange Act Rule 14d-1(d) (Cross-Border Third-Party Tender Offer)	☐

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the registration statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

The information contained in this document is not complete and may be changed. A registration statement relating to these securities has been filed with the U.S. Securities and Exchange Commission. These securities may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective. This document is not an offer to sell these securities, and is not soliciting an offer to buy these securities, nor shall there be any sale of these securities, in any jurisdiction where such offer, solicitation or sale is not permitted or would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction.

PRELIMINARY—SUBJECT TO COMPLETION—DATED February 6, 2023

BUSINESS COMBINATION PROPOSED—YOUR VOTE IS VERY IMPORTANT



Management Information and Proxy Circular and Prospectus of	Proxy Statement of
NIOCORP DEVELOPMENT LTD.	GX ACQUISITION CORP. II

To the Shareholders of NioCorp Developments Ltd. and the Stockholders of GX Acquisition Corp. II:

On September 25, 2022, NioCorp Developments Ltd., a company organized under the laws of the Province of British Columbia (“NioCorp”), GX Acquisition Corp. II, a Delaware corporation (“GX”), and Big Red Merger Sub Ltd, a Delaware corporation and a direct, wholly owned subsidiary of NioCorp (“Merger Sub”), entered into a Business Combination Agreement (the “Business Combination Agreement”), pursuant to which, among other transactions, the following transactions will occur: (i) Merger Sub will merge with and into GX, with GX surviving the merger (the “First Merger”); (ii) all Class A shares in GX (the “GX Class A Shares”) that are held by stockholders (the “GX Public Stockholders”) who have not elected to exercise their redemption rights in connection with the Transactions shall be converted into shares of Class A common stock in GX (such shares, the “First Merger Class A Shares”), as the surviving company in the First Merger; (iii) NioCorp will purchase all First Merger Class A Shares in exchange for common shares, no par value, of NioCorp (“NioCorp Common Shares”) (the “Exchange”); (iv) NioCorp will assume the GX Warrant Agreement and each GX Warrant that was issued and outstanding immediately prior to the effective time of the Exchange will be converted into a warrant to acquire NioCorp Common Shares (a “NioCorp Assumed Warrant”); (v) all of the First Merger Class A Shares will be contributed by NioCorp to 0896800 B.C. Ltd., a company organized under the laws of the Province of British Columbia and a direct, wholly owned subsidiary of NioCorp (“Intermediate Holdco”), in exchange for additional shares of Intermediate Holdco, resulting in GX becoming a direct subsidiary of Intermediate Holdco; (vi) Elk Creek Resources Corp., a Nebraska corporation and a direct, wholly owned subsidiary of Intermediate Holdco (“ECRC”), will merge with and into GX, with GX surviving the merger as a direct subsidiary of Intermediate Holdco (the “Second Merger”); and (vii) following the effective time of the Second Merger, each of NioCorp and GX, as the surviving company of the Second Merger, will effectuate a reverse stock split with the ratio to be mutually agreed by the parties. We refer to the transactions contemplated by the Business Combination Agreement and the Ancillary Agreements collectively as the “Transactions.” As a result of the Transactions, GX will become a subsidiary of NioCorp. Capitalized terms used in this letter but not otherwise defined have the meanings given to them in the accompanying joint proxy statement/prospectus. See “Frequently Used Terms.”

Pursuant to the Business Combination Agreement, upon consummation of the First Merger, each GX Class A Share that is held by a GX Public Stockholder shall be converted into a First Merger Class A Share. In connection with the Exchange, NioCorp will exercise its unilateral option to purchase each First Merger Class A Share in exchange for 11.1829212 NioCorp Common Shares. As a result, each GX Public Stockholder who does not elect to exercise their redemption rights in connection with the Transactions will ultimately be issued NioCorp Common Shares.

Pursuant to the Business Combination Agreement, upon consummation of the First Merger, each Class B share in GX (other than certain shares that may be forfeited in accordance with the GX Support Agreement) will be converted into one share of Class B common stock in GX (such shares, the “First Merger Class B Shares”), as the surviving company in the First Merger. Upon consummation of the Second Merger, each of the First Merger Class B Shares shall be converted into 11.1829212 Class B common shares of GX (each, a “Second Merger Class B Share”), as the surviving company in the Second Merger, in a private placement. Each Second Merger Class B Share will be exchangeable into NioCorp Common Shares on a one-for-one basis, subject to certain equitable adjustments.

shall be exercisable solely for NioCorp Common Shares, and the number of NioCorp Common Shares subject to each NioCorp Assumed Warrant shall be equal to the number of shares of GX Common Stock subject to the applicable GX Warrant multiplied by 11.1829212, with the applicable exercise price adjusted accordingly.

Following the effective time of the Second Merger, NioCorp will effectuate a reverse stock split of the issued NioCorp Common Shares and GX will effectuate a proportionate reverse stock split of the Second Merger Class A Shares and Second Merger Class B Shares at a to-be-determined ratio.

Immediately following completion of the Transactions, it is expected that the current NioCorp Shareholders and the current GX Stockholders will own 42% and 58%, respectively, of the outstanding NioCorp Common Shares (assuming no redemptions by GX Stockholders and that all of the Second Merger Class B Shares are exchanged into NioCorp Common Shares, and not including the potential dilutive impact of the Yorkville Financings).

The accompanying joint proxy statement/prospectus constitutes a prospectus of NioCorp with respect to the registration of 510,686,738 NioCorp Common Shares and 15,666,667 NioCorp Assumed Warrants issuable to GX Securityholders pursuant to the Business Combination Agreement.

In connection with the Transactions, NioCorp has also entered into definitive agreements with respect to the following private placement financings with YA II PN, Ltd., an investment fund managed by Yorkville Advisors Global, LP (together with YA II PN, Ltd., “Yorkville”): (i) $16,000,000 of unsecured convertible debentures of NioCorp convertible into NioCorp Common Shares and NioCorp Common Share purchase warrants entitling the holders thereof to purchase additional NioCorp Common Shares (the “Yorkville Convertible Debt Financing”); and (ii) a standby equity purchase facility pursuant to which NioCorp will have the right, but not the obligation, subject to the conditions set out therein, to sell NioCorp Common Shares to Yorkville with a maximum aggregate value of $65,000,000 (the “Yorkville Equity Facility Financing” and, together with the Yorkville Convertible Debt Financing, the “Yorkville Financings”). Once completed, the Yorkville Financings could provide NioCorp with access to up to an additional $80,360,000, before related fees and expenses payable by NioCorp.

The NioCorp Common Shares are traded on the Toronto Stock Exchange (the “TSX”) under the symbol “NB” and on the OTC Markets trading platform under the symbol “NIOBF.” GX units, GX Class A Shares and public GX Warrants are currently listed on The Nasdaq Stock Market LLC (“Nasdaq”), under the symbols “GXIIU,” “GXII” and “GXIIW,” respectively. NioCorp currently anticipates that, following the Transactions, the NioCorp Common Shares will trade on Nasdaq under the symbol “NB” and will continue to trade on the TSX under the symbol “NB.” In addition, NioCorp anticipates that, following the Transactions, the NioCorp Assumed Warrants will trade on Nasdaq under the symbol “NIOBW.” NioCorp intends to apply for listing of the NioCorp Common Shares and NioCorp Assumed Warrants on Nasdaq and to apply for listing of the NioCorp Common Shares to be issued in connection with the Transactions and the Yorkville Financings on the TSX. Neither Nasdaq nor TSX has conditionally approved any NioCorp listing application and there is no assurance that such exchanges will approve any listing application.

NioCorp will hold a special meeting of shareholders (the “NioCorp Shareholder Meeting”), and GX will hold a special meeting of stockholders (the “GX Stockholder Meeting”), to vote on the proposals necessary to complete the Transactions. We encourage you to obtain current quotes or trading prices for your NioCorp or GX securities before voting at the NioCorp Shareholder Meeting or the GX Stockholder Meeting.

At the NioCorp Shareholder Meeting, NioCorp Shareholders will be asked to consider and approve (i) the issuance of NioCorp Common Shares in connection with the Transactions (the “Share Issuance Proposal”), (ii) the issuance of NioCorp Common Shares in connection with the Yorkville Equity Facility Financing (the “Yorkville Equity Facility Financing Proposal”), (iii) the issuance of NioCorp Common Shares in connection with the Yorkville Convertible Debt Financing (the “Yorkville Convertible Debt Financing Proposal”), (iv) with or without amendment, an amendment to the NioCorp Articles to require the presence, in person or by proxy, of two or more shareholders representing at least 33 1/3% of the outstanding shares entitled to be voted in order to constitute a quorum at any meeting of NioCorp Shareholders (the “Quorum Amendment Proposal”), and (v) a proposal to adjourn the NioCorp Shareholder Meeting to a later date to permit further solicitation and vote of proxies, if necessary (collectively, the “NioCorp Proposals”). Approval of each of these proposals requires the affirmative vote of a majority of votes cast by NioCorp Shareholders entitled to vote thereon and present in person or represented by proxy at the NioCorp Shareholder Meeting. The NioCorp Board recommends that NioCorp Shareholders vote “FOR” each of the NioCorp Proposals to be considered at the NioCorp Shareholder Meeting.

At the GX Stockholder Meeting, GX Stockholders will be asked to consider and approve (i) the Transactions, (ii) the material changes in the proposed amendments to the current Amended and Restated Certificate of Incorporation of GX (the “GX Existing Charter”), the GX Charter Amendment (to be effective immediately prior to the effective time of the First Merger) and the GX Proposed Charter as a whole, which includes the approval of all other changes in the GX Proposed Charter that will replace the GX Existing Charter, as amended by the GX Charter Amendment, as of the Closing, and (iii) a proposal to adjourn the GX Stockholder Meeting to a later date or dates, if necessary, to permit further solicitation and vote of proxies if,

based upon the tabulated vote at the time of the GX Stockholder Meeting, there are not sufficient votes to approve one or more proposals presented to stockholders for a vote (collectively, the “GX Proposals”). The GX Board recommends that GX Stockholders vote “FOR” each of the GX Proposals to be considered at the GX Stockholder Meeting.

Your vote on these matters is very important, regardless of the number of shares you own. Whether or not you plan to attend your company’s respective meeting, please vote by proxy over the internet or telephone using the instructions included with the accompanying proxy card, or promptly complete your proxy card and return it in the enclosed postage-paid envelope, in order to authorize the individuals named on your proxy card to vote your shares at the applicable meeting.

The accompanying joint proxy statement/prospectus provides you with important information about NioCorp, GX, the Transactions, the Business Combination Agreement and the meetings and incorporates important business and financial information about NioCorp and GX that is not included or delivered with the accompanying joint proxy statement/prospectus. This information is available without charge to security holders upon written or oral request. The request should be sent to NioCorp Developments Ltd., 7000 South Yosemite Street, Suite 115, Centennial, Colorado 80112, (855) 264-6267 Attn: Corporate Secretary or GX Acquisition Corp. II, 1325 Avenue of the Americas, 28th Floor, New York, NY 10019, Attn: Michael G. Maselli. To obtain timely delivery of requested materials, security holders must request the information no later than five business days before the date they submit their proxies or attend the special meeting. The latest date to request the information to be received timely is , .

We encourage you to read the entire document carefully, particularly the information under “Risk Factors” beginning on page [●] for a discussion of certain risks relevant to the Transactions.

We look forward to the successful completion of the Transactions.

Sincerely,

Mark A. Smith	Jay R. Bloom
Chief Executive Officer	Co-Chairman and Chief Executive Officer
NioCorp Developments Ltd.	GX Acquisition Corp. II

Neither the U.S. Securities and Exchange Commission, any U.S. state or Canadian provincial or territorial securities commissions, nor similar securities regulatory authority has approved or disapproved of the securities to be issued under this joint proxy statement/prospectus or determined that this joint proxy statement/prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The accompanying joint proxy statement/prospectus is dated , 2023 and is first being mailed or otherwise delivered to NioCorp Shareholders and GX Stockholders on or about , 2023.

NIOCORP DEVELOPMENTS LTD.

7000 SOUTH YOSEMITE STREET, SUITE 115
CENTENNIAL, CO 80112
(720) 639-4647

NOTICE OF SPECIAL MEETING OF SHAREHOLDERS
TO BE HELD ON , 2023

NOTICE IS HEREBY GIVEN THAT a special meeting of shareholders (the “NioCorp Shareholder Meeting”) of NioCorp Developments Ltd. (“we” or “NioCorp”) will be held on March 6, 2023, at at 7000 South Yosemite Street, Centennial, CO 80112 for the following purposes:

●

Proposal No. 1 — The “Share Issuance Proposal” — to approve the issuance of common shares of NioCorp, and including the possible creation of GX Sponsor II LLC as a control person, in connection with the transactions contemplated by the Business Combination Agreement, dated September 25, 2022 (as may be amended from time to time, the “Business Combination Agreement”), by and among GX Acquisition Corp. II, a Delaware corporation (“GX”), NioCorp, and Big Red Merger Sub Ltd, a Delaware corporation and a direct, wholly owned subsidiary of NioCorp. We refer to the transactions contemplated by the Business Combination Agreement collectively as the “Transactions.” The Business Combination Agreement is attached as Annex A to, and is described in more detail in, the accompanying joint proxy statement/prospectus;

●

Proposal No. 2 — The “Yorkville Equity Facility Financing Proposal” —to approve the issuance of all of the common shares of NioCorp that may be issuable upon a sale at the Purchase Price (as defined in the accompanying joint proxy statement/prospectus) and all of the Commitment Shares (as defined in the accompanying joint proxy statement/prospectus) to be issued, in each case, in connection with the transactions (the “Yorkville Equity Facility Financing”) contemplated by the Standby Equity Purchase Agreement, dated January 26, 2023 (as may be amended from time to time, the “Yorkville Equity Facility Financing Agreement”), by and between NioCorp and YA II PN, Ltd., an investment fund managed by Yorkville Advisors Global, LP (together with YA II PN, Ltd., “Yorkville”);

●

Proposal No. 3 — The “Yorkville Convertible Debt Financing Proposal” — to approve the issuance of all of the convertible debentures of NioCorp that may be issuable, all of the warrants of NioCorp that may be issuable, and all of the common shares of NioCorp that may be issuable upon conversion of the principal amount of, and any and all accrued interest on, the convertible debentures at the Conversion Price (as defined in the accompanying joint proxy statement/prospectus) and upon exercise of the warrants, in each case, in connection with the transactions (the “Yorkville Convertible Debt Financing”) contemplated by the Securities Purchase Agreement, dated January 26, 2023 (as may be amended from time to time, the “Yorkville Convertible Debt Financing Agreement”), by and between NioCorp and Yorkville;

●

Proposal No. 4 — The “Quorum Amendment Proposal” — to approve, with or without amendment, an amendment to the NioCorp Articles to require the presence, in person or by proxy, of two or more shareholders representing at least 33 1/3% of the outstanding shares entitled to be voted in order to constitute a quorum at any meeting of NioCorp Shareholders, the form of which amendment to the Articles is attached as Annex B to the accompanying joint proxy statement/prospectus; and

●

Proposal No. 5 — The “Adjournment Proposal” — to consider and vote upon a proposal to adjourn the NioCorp Shareholder Meeting to a later date or dates, if necessary, to permit further solicitation and vote of proxies if, based upon the tabulated vote at the time of the NioCorp Shareholder Meeting, there are not sufficient votes to approve one or more proposal presented to shareholders for vote.

The approval of each of these proposals (collectively, the “NioCorp Proposals”) requires the affirmative vote of a majority of votes cast by shareholders of NioCorp entitled to vote thereon and present in person or represented by proxy at the NioCorp Shareholder Meeting. We cannot complete the Transactions unless each of the Share Issuance Proposal and the Quorum Amendment Proposal are approved at the NioCorp Shareholder Meeting. We cannot complete the Yorkville Convertible Debt Financing if the Yorkville Convertible Debt Financing Proposal is not approved at the NioCorp Shareholder Meeting, and we cannot complete the Yorkville Equity Facility Financing if the Yorkville Equity Facility Financing Proposal is not approved at the NioCorp Shareholder Meeting.

None of the NioCorp Proposals are conditioned on the approval of any other NioCorp Proposal, as more fully described in the accompanying joint proxy statement/prospectus.

However, the Yorkville Equity Facility Financing Agreement and the Yorkville Convertible Debt Financing Agreement will terminate pursuant to their terms if the Business Combination Agreement is terminated.

Being made available along with this Notice of Meeting are (i) the Management Information and Proxy Circular included as part of the accompanying joint proxy statement/prospectus and (ii) a form of proxy and notes thereto (together, the “NioCorp Meeting Materials”).

The NioCorp Board of Directors has unanimously resolved (i) that the Transactions are fair to the NioCorp Shareholders and (ii) that the Transactions and entering into of the Business Combination Agreement, the other ancillary agreements contemplated thereby, the Yorkville Equity Facility Financing Agreement and the Yorkville Convertible Debt Financing Agreement are in the best interests of NioCorp and unanimously recommends that NioCorp Shareholders vote “FOR” each proposal. The accompanying joint proxy statement/prospectus provides a detailed description of the Business Combination Agreement and the related agreements and Transactions. We urge you to read the accompanying joint proxy statement/prospectus, including any documents incorporated by reference into the accompanying joint proxy statement/prospectus, and its annexes carefully and in their entirety.

The NioCorp Board of Directors has fixed February 1, 2023 as the record date for the NioCorp Shareholder Meeting. NioCorp Shareholders at the close of business on February 1, 2023, will be entitled to receive notice of, attend, and vote at the NioCorp Shareholder Meeting.

YOUR VOTE IS VERY IMPORTANT. If you are a registered shareholder of NioCorp and are unable to attend the NioCorp Shareholder Meeting, you may vote: (i) via the Internet; (ii) by calling a toll-free telephone number; or (iii) if you received your proxy materials by mail, by dating and executing the form of proxy for the NioCorp Shareholder Meeting and depositing it by hand delivery or by mail with Computershare Investor Services Inc., Proxy Dept., 100 University Avenue, 8th Floor, Toronto, Ontario, M5J 2Y1 or by facsimile to 1-866-249-7775 (within North America) or 1-416-263-9524 (outside North America). Instructions for telephone and Internet voting are included in the notice that NioCorp mailed to shareholders on or about , 2023. All instructions are also listed in the form of proxy and notes thereto. Your proxy or voting instructions must be received in each case no later than , Mountain time, on , 2023, or no later than 48 hours before the NioCorp Shareholder Meeting is reconvened following any adjournment or postponement.

If you are a non-registered shareholder of NioCorp and receive these materials through your broker or another intermediary, please complete and return the materials in accordance with the instructions provided to you by your broker or such other intermediary.

The NioCorp Meeting Materials are first being made available to shareholders of NioCorp on or about , 2023.

DATED at Centennial, Colorado, this day of , 2023.


	By Order of the Board of Directors,
	Mark A. Smith
	Chief Executive Officer

GX ACQUISITION CORP. II

1325 Avenue of the Americas, 28th Floor,
New York, NY, 10019
(212) 616-3700

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS
TO BE HELD ON , 2023

To the Stockholders of GX Acquisition Corp. II:

NOTICE IS HEREBY GIVEN that a special meeting of stockholders (the “GX Stockholder Meeting”) of GX Acquisition Corp. II, a Delaware corporation (“GX”, “we”, “our” or “us”), will be held on , 2023, at , Eastern time, via live webcast at the following address: https://www.cstproxy.com/gx2/2023. You will need the 12-digit meeting control number that is printed on your proxy card to enter the GX Stockholder Meeting. GX recommends that you log in at least 15 minutes before the GX Stockholder Meeting to ensure you are logged in when the GX Stockholder Meeting starts. Please note that you will not be able to attend the GX Stockholder Meeting in person. You are cordially invited to attend the GX Stockholder Meeting for the following purposes:

●

Proposal No. 1 — The “Business Combination Proposal” — to consider and vote upon a proposal to approve and adopt the Business Combination Agreement, dated September 25, 2022 (as may be amended from time to time, the “Business Combination Agreement”), by and among GX, NioCorp Developments Ltd., a company organized under the laws of the Province of British Columbia (“NioCorp”), and Big Red Merger Sub Ltd, a Delaware corporation and a direct wholly owned subsidiary of NioCorp (“Merger Sub”), and the transactions contemplated thereby, pursuant to which, among other transactions, the following transactions will occur: (i) Merger Sub will merge with and into GX, with GX surviving the merger (the “First Merger”); (ii) all Class A shares in GX (the “GX Class A Shares”) that are held by stockholders (the “GX Public Stockholders”) who have not elected to exercise their redemption rights in connection with the Transactions (as defined below) shall be converted into shares of Class A common stock in GX (such shares, the “First Merger Class A Shares”), as the surviving company in the First Merger; (iii) NioCorp will purchase all First Merger Class A Shares in exchange for common shares of NioCorp (“NioCorp Common Shares”) (the “Exchange”); (iv) NioCorp will assume the GX Warrant Agreement and each GX Warrant (each as defined below) that was issued and outstanding immediately prior to the effective time of the Exchange will be converted into a warrant to acquire NioCorp Common Shares (a “NioCorp Assumed Warrant”); (v) all of the First Merger Class A Shares will be contributed by NioCorp to 0896800 B.C. Ltd., a company organized under the laws of the Province of British Columbia and a direct, wholly owned subsidiary of NioCorp (“Intermediate Holdco”), in exchange for additional shares of Intermediate Holdco, resulting in GX becoming a direct subsidiary of Intermediate Holdco; (vi) Elk Creek Resources Corp., a Nebraska corporation and a direct, wholly owned subsidiary of Intermediate Holdco (“ECRC”), will merge with and into GX, with GX surviving the merger as a direct subsidiary of Intermediate Holdco (the “Second Merger”); and (vii) following the effective time of the Second Merger, each of NioCorp and GX, as the surviving company of the Second Merger, will effectuate the applicable reverse stock split. We refer to the transactions contemplated by the Business Combination Agreement collectively as the “Transactions”.

●

Proposal No. 2 — The “Charter Amendment Proposal” — to consider and vote upon a proposal to approve the amendment to the current Amended and Restated Certificate of Incorporation of GX (the “GX Existing Charter”), as of immediately prior to the effective time of the First Merger, to remove the automatic conversion of GX Founder Shares into GX Class A Shares (such amendment, the “GX Charter Amendment”). A copy of the GX Charter Amendment is attached to the accompanying joint proxy statement/prospectus as Annex C.

●

Proposal No. 3 through No. 9 — The “Charter Proposal” —

to consider and vote upon seven separate non-binding, advisory proposals to approve the following material differences in the proposed updated Amended and Restated Certificate of Incorporation of GX (the “GX Proposed Charter”) that will replace the GX Existing Charter, as amended by the GX Charter Amendment, as of the Closing. A copy of the GX Proposed Charter is attached to the accompanying joint proxy statement/prospectus as Annex D;

iii

a non-binding, advisory proposal to increase the number of authorized shares of GX Class A Shares and GX Founder Shares (Proposal No. 3);

a non-binding, advisory proposal to increase the number of authorized shares of preferred stock of GX (Proposal No. 4);

a non-binding, advisory proposal to declassify the board of directors from three classes to one class (Proposal No. 5);

a non-binding, advisory proposal to provide for the election or removal of directors only upon the vote of holders of GX Class A shares (Proposal No. 6);

a non-binding, advisory proposal to require the affirmative vote, approval or consent of the holders of a majority of the GX Founder Shares then held by Exchanging Shareholders (as defined in the Exchange Agreement), voting as a separate class, to amend, alter, change or repeal any provision of the GX Proposed Charter which affects the rights, preferences and privileges of the holders of GX Founder Shares in any material respect (Proposal No. 7);

a non-binding, advisory proposal to eliminate certain provisions related to the consummation of an initial business combination that will no longer be relevant following the Closing (such as Article IX, which sets forth various provisions related to our operations as a blank check company prior to the consummation of an initial business combination, including with respect to redemptions and the trust account (the “Trust Account”)) (Proposal No. 8); and

a non-binding, advisory proposal, conditioned upon the approval of Proposals No. 3 through No. 8, to approve the GX Proposed Charter as a whole, which includes the approval of all other changes in the GX Proposed Charter that will replace the GX Existing Charter, as amended by the GX Charter Amendment, as of the Closing (Proposal No. 9 and together with Proposals No. 3 through No. 8, the “Charter Proposal”).

The non-binding, advisory proposals in GX Proposals No. 3 through No. 9 will not apply to the existing holders of GX Class A Shares because they will not continue to be direct stockholders of GX, as GX will be a subsidiary of NioCorp following the consummation of the Transactions.

●

Proposal No. 10 — The “Adjournment Proposal” — to consider and vote upon a proposal to adjourn the GX Stockholder Meeting to a later date or dates, if necessary, to permit further solicitation and vote of proxies if, based upon the tabulated vote at the time of the GX Stockholder Meeting, there are not sufficient votes to approve one or more proposals presented to stockholders for a vote.

Only holders of record of GX Class A Shares and GX Founder Shares at the close of business on , 2023 are entitled to notice of the GX Stockholder Meeting and to vote at the GX Stockholder Meeting and any adjournments or postponements of the GX Stockholder Meeting. A complete list of GX’s stockholders of record entitled to vote at the GX Stockholder Meeting will be available for ten days before the GX Stockholder Meeting at GX’s principal executive offices for inspection by stockholders during ordinary business hours for any purpose germane to the GX Stockholder Meeting.

Pursuant to the GX Existing Charter, we are providing the holders of GX Class A Shares originally sold as part of the GX Public Units issued in our initial public offering (the “IPO” and such holders, the “GX Public Stockholders”) with the opportunity to redeem, upon the closing of the Transactions (the “Closing”), GX Class A Shares then held by them for cash equal to their pro rata share of the aggregate amount on deposit (as of two business days prior to the Closing) in the Trust Account that holds the proceeds (including interest not previously released to GX to pay its taxes) from the IPO and a concurrent private placement of warrants to GX Sponsor II LLC (the “Sponsor”). For illustrative purposes, based on the fair value of cash and marketable securities held in the Trust Account as of January 13, 2023 of approximately $303,560,016, the estimated per share redemption price would have been approximately $10.11. GX Public Stockholders may elect to redeem their shares whether or not they are holders as of the record date and whether or not they vote “FOR” the Business Combination Proposal. Notwithstanding the foregoing redemption rights, a GX Public Stockholder, together with any of his, her or its affiliates or any other person with whom he, she or it is acting in concert or as a “group” (as defined under Section 13(d)(3) of the Securities Exchange Act of 1934, as amended), will be restricted from redeeming in the aggregate his, her or its shares or, if part of such a group, the group’s shares, in excess of 15% of the outstanding GX Class A Shares sold in the IPO. Holders of outstanding GX Warrants sold in the IPO, which are exercisable for GX Class A Shares under certain circumstances, do not have redemption rights in connection with the Transactions. GX’s

Sponsor, officers and directors have agreed to waive their redemption rights in connection with the consummation of the Transactions with respect to any GX Founder Shares they hold and any GX Class A Shares they may have acquired during or after the IPO. GX Founder Shares will be excluded from the pro rata calculation used to determine the per share redemption price. Currently, GX’s Sponsor, officers and directors own approximately 20.0% of the outstanding issued and outstanding shares of GX Common Stock, including all of the GX Founder Shares. GX’s Sponsor, officers and directors have, for no additional consideration, agreed to vote any GX Class A Shares and GX Founder Shares owned by them in favor of the Transactions.

We may not consummate the Transactions unless each of the Business Combination Proposal, the Charter Amendment Proposal and the Charter Proposal is approved at the GX Stockholder Meeting. Each GX Proposal other than the Adjournment Proposal is conditioned on the approval of each other GX Proposal other than the Adjournment Proposal. The Adjournment Proposal is not conditioned on the approval of any other GX Proposal set forth in the accompanying joint proxy statement/prospectus.

The Board of Directors of GX has unanimously approved the Business Combination Agreement and the Transactions and recommends that you vote “FOR” the Business Combination Proposal, “FOR” the Charter Amendment Proposal, “FOR” the Charter Proposal and “FOR” the Adjournment Proposal.

Your attention is directed to the joint proxy statement/prospectus accompanying this notice (including the financial statements and annexes attached thereto) for a more complete description of the proposed Transactions and each of the proposals. You are encouraged to read this joint proxy statement/prospectus carefully. If you have any questions or need assistance voting your shares, please call GX’s proxy solicitor, Morrow Sodali LLC, at (800) 662-5200; banks and brokers can call collect at (203) 658-9400.

		By Order of the Board of Directors,



, 2023
		Jay R. Bloom Co-Chairman and Chief Executive Officer

TABLE OF CONTENTS

	Page

FREQUENTLY USED TERMS	1
ABOUT THIS JOINT PROXY STATEMENT/PROSPECTUS	5
PRESENTATION OF FINANCIAL INFORMATION	5
MINERAL RESERVES AND RESOURCES	6
QUESTIONS AND ANSWERS ABOUT THE TRANSACTIONS	7
QUESTIONS AND ANSWERS ABOUT THE NIOCORP SHAREHOLDER MEETING	14
QUESTIONS AND ANSWERS ABOUT THE GX STOCKHOLDER MEETING	18
SUMMARY	26
SELECTED HISTORICAL CONSOLIDATED FINANCIAL AND OTHER DATA	45
COMPARATIVE MARKET PRICE INFORMATION	47
CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS	48
RISK FACTORS	51
UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION	75
NOTES TO THE UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION	81
COMPARATIVE PER SHARE INFORMATION	86
NIOCORP SPECIAL MEETING OF SHAREHOLDERS	88
NIOCORP PROPOSAL NO. 1 — THE SHARE ISSUANCE PROPOSAL	94
NIOCORP PROPOSAL NO. 2 — THE YORKVILLE EQUITY FACILITY FINANCING PROPOSAL	96
NIOCORP PROPOSAL NO. 3 — THE YORKVILLE CONVERTIBLE DEBT FINANCING PROPOSAL	98
NIOCORP PROPOSAL NO. 4 — THE QUORUM AMENDMENT PROPOSAL	101
NIOCORP PROPOSAL NO. 5 — THE ADJOURNMENT PROPOSAL	102
GX SPECIAL MEETING OF STOCKHOLDERS	103
GX PROPOSAL NO. 1 — THE BUSINESS COMBINATION PROPOSAL	109
GX PROPOSAL NO. 2 — THE CHARTER AMENDMENT PROPOSAL	114
GX PROPOSAL NO. 3 THROUGH NO. 9 — THE CHARTER PROPOSAL	115
GX PROPOSAL NO. 10 — THE ADJOURNMENT PROPOSAL	119
THE TRANSACTIONS	120
THE BUSINESS COMBINATION AGREEMENT	151
ANCILLARY AGREEMENTS	160
YORKVILLE FINANCINGS	162
MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS	170
MATERIAL CANADIAN FEDERAL INCOME TAX CONSIDERATIONS	180
INFORMATION ABOUT NIOCORP	188
INFORMATION ABOUT GX	191

- i -

TABLE OF CONTENTS

(continued)

	Page

GX’S MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS	197
CERTAIN GX RELATIONSHIPS AND RELATED PARTY TRANSACTIONS	202
MANAGEMENT AFTER THE TRANSACTIONS	205
DESCRIPTION OF SECURITIES	213
SHARES ELIGIBLE FOR FUTURE SALE	216
COMPARISON OF SHAREHOLDERS’ RIGHTS	218
SECURITY OWNERSHIP OF CERTAIN GX BENEFICIAL OWNERS AND MANAGEMENT	235
SECURITY OWNERSHIP OF CERTAIN NIOCORP BENEFICIAL OWNERS AND MANAGEMENT	239
ADDITIONAL INFORMATION	241
LEGAL MATTERS	242
EXPERTS	242
WHERE YOU CAN FIND ADDITIONAL INFORMATION	243

Annex A: Business Combination Agreement	A-1
Annex B: Proposed Amendment to Articles of NioCorp	B-1
Annex C: Proposed GX Charter Amendment	C-1
Annex D: Proposed GX Charter	D-1
Annex E: Opinion of GenCap Mining Advisory Ltd.	E-1
Annex F: Opinion of Scalar, LLC	F-1
Annex G: Form of Registration Rights and Lock-Up Agreement	G-1
Annex H: Form of Exchange Agreement	H-1
Annex I: NioCorp Support Agreement	I-1
Annex J: GX Support Agreement	J-1
Annex K: Form of NioCorp Developments Ltd. Proxy Card	K-1
Annex L: Form of GX Acquisition Corp. II Proxy Card	L-1

- ii -

FREQUENTLY USED TERMS

“Ancillary Agreements” means, collectively, the Registration Rights and Lock-Up Agreement, the Exchange Agreement, the GX Support Agreement, the NioCorp Support Agreement and the Key Employee Agreements and each other schedule, instrument or certificate contemplated by the Business Combination Agreement or by any of the foregoing.

“BCBCA” means the Business Corporations Act (British Columbia).

“Business Combination Agreement” means the Business Combination Agreement, dated September 25, 2022, by and among GX, NioCorp and Merger Sub, as may be amended from time to time.

“Cash Transaction Expenses” means the sum of (a) GX's unpaid transaction expenses accruing at or prior to the Closing and (b) NioCorp's unpaid transaction expenses accruing at or prior to the Closing.

“Closing” means the closing of the Transactions.

“Closing Cash Minimum” means $15,000,000 less the amount, if any, by which the Cash Transaction Expenses are, in the aggregate, reduced to less than $15,000,000, as a direct result of Sponsor's forfeiture or transfer of GX Common Shares in exchange for reducing the cash amounts that would otherwise be payable to a third party with respect to Cash Transaction Expenses.

“Code” means the Internal Revenue Code of 1986, as amended, and the rules and regulations issued thereunder.

“Combined Company” means NioCorp following the completion of the Transactions.

“Company Operating Cash” means cash raised by NioCorp after the signing of the Business Combination Agreement for the sole purpose of funding cash expenses of NioCorp and its subsidiaries in transactions agreed to in writing by GX (such consent not to be unreasonably withheld, conditioned or delayed), up to a cap in the amount to be mutually agreed between GX and NioCorp following the signing of the Business Combination Agreement, taking into account the reasonable operating cash needs of NioCorp (such cap, the “Company Operation Cash Cap”).

“Contribution” means the contribution by NioCorp, immediately following the Exchange Time, of all of the First Merger Class A Shares to Intermediate Holdco in exchange for additional shares in Intermediate Holdco (such time, the “Contribution Time”).

“DGCL” means the Delaware General Corporation Law.

“ECRC” means Elk Creek Resources Corp., a private Nebraska corporation and a direct wholly owned subsidiary of Intermediate Holdco.

“Equity Facility” means the standby equity purchase facility pursuant to which NioCorp will have the right, but not the obligation, subject to the conditions set out therein, to sell NioCorp Common Shares to Yorkville with a maximum aggregate value of $65,000,000.

“Exchange” means the purchase by NioCorp, immediately following the First Merger Effective Time, of all First Merger Class A Shares not held by NioCorp from the holder thereof in exchange for 11.1829212 NioCorp Common Shares per share, as described in the Business Combination Agreement (such time, the “Exchange Time”).

“Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder.

“Exchange Agent” means the exchange agent under the Exchange Agreement, such agent to be agreed upon by GX and NioCorp prior to the Closing.

“Exchange Agreement” means the exchange agreement to be entered into by and among NioCorp, GX and Sponsor at the Closing.

“Exchange Ratio” means 11.1829212.

“First Merger” means the merger of Merger Sub with and into GX, with GX surviving the First Merger as the “First Merger Surviving Company.”

“First Merger Class A Shares” means the issued and outstanding GX Class A Shares that are not Redemption Shares.

“First Merger Effective Time” means the date and time of the filing of the certificate of merger for the First Merger pursuant to Section 252(c) of the DGCL with the Secretary of State of Delaware, or such later time as is specified in such filing.

“GAAP” means the United States generally accepted accounting principles, consistently applied.

“GX” means GX Acquisition Corp. II, a Delaware corporation.

“GX Board” means the Board of Directors of GX.

“GX Bylaws” means the bylaws of GX.

“GX Class A Shares” means the Class A shares of GX.

“GX Common Stock” means, collectively, the GX Class A Shares and the GX Founder Shares.

“GX Existing Charter” means the current Amended and Restated Certificate of Incorporation of GX.

“GX Founder Shares” means the Class B shares of GX, all of which are held by Sponsor.

“GX Founder Warrants” means the share purchase warrants issued to Sponsor at the closing of the IPO.

“GX Proposals” means the special resolution of GX Stockholders to approve (i) the Transactions, (ii) the GX Charter Amendment, the material differences in the GX Proposed Charter, and the GX Proposed Charter as a whole, which includes the approval of all other changes in the GX Proposed Charter that will replace the GX Existing Charter, as amended by the GX Charter Amendment, as of the Closing, and (iii) a proposal to adjourn the GX Stockholder Meeting to a later date or dates, if necessary, to permit further solicitation and vote of proxies if, based upon the tabulated vote at the time of the GX Stockholder Meeting, there are not sufficient votes to approve one or more proposals presented to stockholders for a vote.

“GX Proposed Charter” means the proposed amendment to the Amended and Restated Certificate of Incorporation of GX.

“GX Public Stockholders” means GX Stockholders who hold GX Class A Shares.

“GX Public Units” means the units of GX issued pursuant to the IPO comprised of (a) one GX Class A Share and (b) one-third of a GX Public Warrant.

“GX Public Warrants” means the share purchase warrants of GX entitling the holder thereof to purchase one GX Class A Share included as a component of the GX Public Units.

“GX Securityholders” means the stockholders of GX and the holders of GX Warrants.

“GX Stockholder Meeting” means the special meeting of GX Stockholders, including any adjournment or postponement of such special meeting in accordance with the terms of the Business Combination Agreement, to be called for the purpose of considering and, if thought fit, approving the GX Proposals.

“GX Stockholders” means the stockholders of GX.

“GX Support Agreement” means the Sponsor Support Agreement, dated as of September 25, 2022, by and among Sponsor, in its capacity as a stockholder of GX, GX, NioCorp and the other parties thereto, pursuant to which Sponsor and certain other GX Stockholders agreed, among other things, to vote in favor of each of the GX Proposals.

“GX Warrant Agreement” means the Warrant Agreement, dated March 17, 2021, between GX and Continental Stock Transfer & Trust Company.

“GX Warrants” means the GX Public Warrants and the GX Founder Warrants.

“Intermediate Holdco” means 0896800 B.C. Ltd., a company organized under the laws of the Province of British Columbia and a direct wholly owned subsidiary of NioCorp.

“IRS” means the U.S. Internal Revenue Service.

“Key Employee Agreements” means the employment agreements entered into between NioCorp and certain key employees of NioCorp, the effectiveness of which is conditioned on the occurrence of the Closing.

“Merger Sub” means Big Red Merger Sub Ltd, a Delaware corporation and a direct wholly owned subsidiary of NioCorp.

“Mergers” means, collectively, the First Merger and the Second Merger.

“Nasdaq” means the Nasdaq Stock Market LLC.

“NI 43-101” means National Instrument 43-101 – “Standards of Disclosure for Mineral Projects” of the Canadian Securities Administrators.

“NioCorp” means NioCorp Developments Ltd., a company incorporated under the laws of the Province of British Columbia.

“NioCorp Amended Articles” means the articles of NioCorp, as amended by the amendment attached hereto as Annex B.

“NioCorp Articles” means NioCorp’s articles, as amended, effective as of January 27, 2015.

“NioCorp Assumed Warrants” means the NioCorp Common Share purchase warrants to be issued by NioCorp at the time of the Exchange as a result of the conversion of GX Warrants that are issued and outstanding immediately prior to the Exchange into warrants to acquire NioCorp Common Shares, with each NioCorp Assumed Warrant to be exercisable for a number of NioCorp Common Shares equal to the number of shares of GX Common Stock subject to the applicable GX Warrant multiplied by 11.1829212.

“NioCorp Board” means the Board of Directors of NioCorp.

“NioCorp Common Shares” means the common shares of NioCorp, no par value.

“NioCorp Convertible Debentures” means the unsecured convertible debentures of NioCorp convertible into NioCorp Common Shares to be issued by NioCorp to Yorkville pursuant to the Yorkville Convertible Debt Financing.

“NioCorp Financing Warrants” means the NioCorp Common Share purchase warrants to be issued by NioCorp to Yorkville pursuant to the Yorkville Convertible Debt Financing.

“NioCorp Notice of Articles” means NioCorp’s notice of articles, dated April 5, 2016.

“NioCorp Proposals” means the resolutions of NioCorp Shareholders to approve (i) the Share Issuance Proposal, (ii) the Yorkville Equity Facility Financing Proposal, (iii) the Yorkville Convertible Debt Financing Proposal, (iv) the Quorum Amendment Proposal and (v) the Adjournment Proposal.

“NioCorp Shareholder Meeting” means the special meeting of NioCorp, including any adjournment or postponement of such meeting, to be called for the purpose of considering and, if thought fit, approving the NioCorp Proposals.

“NioCorp Shareholders” means the shareholders of NioCorp.

“NioCorp Support Agreement” means the Company Support Agreement, dated as of September 25, 2022, by and among GX, NioCorp and the NioCorp Shareholders party thereto, pursuant to which such NioCorp Shareholders agreed, among other things, to vote in favor of each of the NioCorp Proposals.

“Quorum Amendment Proposal” means the resolution of NioCorp Shareholders to approve, with or without amendment, an amendment to the NioCorp Articles to require the presence, in person or by proxy, of two or more shareholders representing at least 33 1/3% of the outstanding shares entitled to be voted in order to constitute a quorum at any meeting of NioCorp Shareholders.

“Redemption Shares” means the GX Class A Shares held by GX Public Stockholders that are redeemed and cancelled in accordance with the GX Existing Charter.

“Registration Rights and Lock-Up Agreement” means the registration rights and lock-up agreement to be entered into at the Closing by and among NioCorp, certain NioCorp Shareholders, GX, the Sponsor, certain GX Stockholders and the other parties thereto, providing for, among other things, certain registration rights and transfer restrictions contained therein.

“S-K 1300” means Subpart 1300 of Regulation S-K of the Securities Act.

“SEC” means the U.S. Securities and Exchange Commission.

“Second Merger” means the merger of ECRC with and into the First Merger Surviving Company, with the First Merger Surviving Company surviving the Second Merger as the “Second Merger Surviving Company.”

“Second Merger Effective Time” means the date and time of the filing of the certificate of merger for the Second Merger pursuant to Section 252(c) of the DGCL with the Secretary of State of Delaware, or such later time as is specified in such filing.

“Securities Act” means the Securities Act of 1933, as amended, and the rules and regulations promulgated thereunder.

“Share Issuance Proposal” means the resolution of NioCorp Shareholders to approve the issuance of NioCorp Common Shares issuable (a) pursuant to the Exchange, (b) upon the exchange of the Second Merger Class B Shares and (c) upon the exercise of the NioCorp Assumed Warrants.

“Sponsor” means GX Sponsor II LLC.

“Transactions” means the transactions contemplated by the Business Combination Agreement and the Ancillary Agreements.

“TSX” means the Toronto Stock Exchange.

“Yorkville” means, collectively, YA II PN, Ltd. and Yorkville Advisors Global, LP.

“Yorkville Convertible Debt Financing” means the issuance of $16,000,000 aggregate principal amount of NioCorp Convertible Debentures and NioCorp Financing Warrants to Yorkville pursuant to the Yorkville Convertible Debt Financing Agreement.

“Yorkville Convertible Debt Financing Agreement” means the Securities Purchase Agreement, dated January 26, 2023, between NioCorp and Yorkville, as may be amended from time to time.

“Yorkville Convertible Debt Financing Proposal” means the resolution of NioCorp Shareholders to approve the issuance of all of the NioCorp Convertible Debentures that may be issuable, all of the NioCorp Financing Warrants that may be issuable, and all of the NioCorp Common Shares that may be issuable upon conversion of the principal amount of, and any and all accrued interest on, the NioCorp Convertible Debentures at the Conversion Price (as defined herein) and upon exercise of the NioCorp Financing Warrants, in each case, in connection with the transactions contemplated by the Yorkville Convertible Debt Financing Agreement.

“Yorkville Equity Facility Financing” means the issuance of NioCorp Common Shares to Yorkville under the Equity Facility pursuant to the Yorkville Equity Facility Financing Agreement.

“Yorkville Equity Facility Financing Agreement” means the Standby Equity Purchase Agreement, dated January 26, 2023, by and between NioCorp and Yorkville, as may be amended from time to time.

“Yorkville Equity Facility Financing Proposal” means the resolution of NioCorp Shareholders to approve the issuance of all of the NioCorp Commons Shares that may be issuable upon a sale at the Purchase Price (as defined herein), and all of the Commitment Shares to be issued, in each case, in connection with the transactions contemplated by the Yorkville Equity Facility Financing Agreement.

“Yorkville Financing Agreements” means the Yorkville Convertible Debt Financing Agreement and the Yorkville Equity Facility Financing Agreement.

“Yorkville Financings” means the Yorkville Convertible Debt Financing and the Yorkville Equity Facility Financing.

ABOUT THIS JOINT PROXY STATEMENT/PROSPECTUS

This joint proxy statement/prospectus, which forms part of a registration statement on Form S-4 (File No. 333-268227) filed with the SEC by NioCorp, constitutes a prospectus of NioCorp under Section 5 of the Securities Act with respect to the NioCorp Common Shares and NioCorp Assumed Warrants issuable to GX Securityholders pursuant to the Business Combination Agreement. This joint proxy statement/prospectus also constitutes (i) a notice of meeting and management information and proxy circular of NioCorp under Section 14(a) of the Exchange Act and under the BCBCA with respect to the NioCorp Shareholder Meeting, at which meeting NioCorp Shareholders will be asked to consider and vote on the NioCorp Proposals and (ii) a notice of meeting and a proxy statement of GX under Section 14(a) of the Exchange Act with respect to the GX Stockholder Meeting, at which meeting GX Stockholders will be asked to consider and vote on the GX Proposals.

You should rely only on the information contained in, or incorporated by reference into, this joint proxy statement/prospectus. No one has been authorized to provide you with information that is different from that contained in, or incorporated by reference into, this joint proxy statement/prospectus. This joint proxy statement/prospectus is dated , 2023. The information contained in this joint proxy statement/prospectus is accurate only as of that date or, in the case of information in a document incorporated by reference, as of the date of such document, unless the information specifically indicates that another date applies. Neither the mailing of this joint proxy statement/prospectus to GX Stockholders nor the issuance by NioCorp of NioCorp Common Shares or NioCorp Assumed Warrants pursuant to the Business Combination Agreement will create any implication to the contrary.

This joint proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction in which it is unlawful to make any such offer or solicitation in such jurisdiction.

The information concerning NioCorp contained in, or incorporated by reference into, this joint proxy statement/prospectus has been provided by NioCorp, and the information concerning GX contained in, or incorporated by reference into, this joint proxy statement/prospectus has been provided by GX.

PRESENTATION OF FINANCIAL INFORMATION

The financial statements of each of NioCorp and GX included elsewhere or incorporated by reference in this joint proxy statement/prospectus have been prepared in accordance with GAAP. Unless otherwise specified, amounts in this joint proxy statement/prospectus are presented in United States (“U.S.”) dollars. Some of NioCorp’s material agreements use Canadian dollars and NioCorp Common Shares, as traded on the TSX, are traded in Canadian dollars. As used herein, “CAD$” represents Canadian dollars.

On October 31, 2022, NioCorp filed Amendment No. 1 on Form 10-K/A to the Annual Report on Form 10-K for the fiscal year ended June 30, 2022 (as amended, the “NioCorp Form 10-K”) to restate certain information in NioCorp’s previously issued consolidated financial statements as of and for the fiscal years ended June 30, 2022 and 2021 and the interim periods ended September 30, 2021, December 31, 2021 and March 31, 2022 (collectively, the “Affected Periods”). Any references in this joint proxy statement/prospectus to NioCorp’s consolidated financial statements for any of the Affected Periods refer to such consolidated financial statements as so restated, which restated consolidated financial statements are incorporated by reference into this joint proxy statement/prospectus. See “Where You Can Find Additional Information.”

MINERAL RESERVES AND RESOURCES

Unless otherwise indicated, information concerning NioCorp’s mining property included or incorporated by reference into this joint proxy statement/prospectus, including mineral resource and reserve estimates, has been prepared in accordance with the requirements of National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”) and the Canadian Institute of Mining and Metallurgy (“CIM”) “Definition Standards – For Mineral Resources and Mineral Reserves, May 10, 2014” (the “CIM Definition Standards”). Beginning with the NioCorp Form 10-K, NioCorp’s mining property disclosures included or incorporated by reference in its SEC filings, including mineral resource and reserve estimates, are required to be prepared in accordance with the requirements of subpart 1300 of Regulation S-K (“S-K 1300”). Previously, NioCorp prepared its estimates of mineral resources and mineral reserves following only NI 43-101 and the CIM Definition Standards. On June 28, 2022, NioCorp issued a CIM-compliant NI 43-101 technical report (the “2022 NI 43-101 Elk Creek Technical Report”) for the Elk Creek Project, which is available through the website maintained by the Canadian Securities Administrators at www.sedar.com. On September 6, 2022, NioCorp filed a technical report summary for the Elk Creek Project that conforms to S-K 1300 reporting standards (the “S-K 1300 Elk Creek Technical Report Summary”) as Exhibit 96.1 to the NioCorp Form 10-K, which is available through the website maintained by the SEC at www.sec.gov. The 2022 NI 43-101 Elk Creek Technical Report and S-K 1300 Elk Creek Technical Report Summary are based on a feasibility study (the “June 2022 Feasibility Study”) prepared by qualified persons (within the meaning of both NI 43-101 and S-K 1300, as applicable) and are substantively identical to one another except for internal references to the regulations under which the report is made, and certain organizational differences. The requirements and standards under Canadian securities laws, however, differ from those under S-K 1300. The terms “mineral resource,” “inferred mineral resource,” “indicated mineral resource,” “mineral reserve,” “probable mineral reserve,” and “proven mineral reserve” included or incorporated by reference herein are used as defined in accordance with NI 43-101 under the CIM Definition Standards. While the terms are substantially similar to the same terms defined under S-K 1300, there are differences in the definitions. Accordingly, there is no assurance any mineral resource or mineral reserve estimates that NioCorp may report under NI 43-101 will be the same as the mineral resource or mineral reserve estimates that NioCorp may report under S-K 1300.

NioCorp discloses estimates of both its mineral resources and mineral reserves. You are cautioned that mineral resources are subject to further exploration and development and are subject to additional risks and no assurance can be given that they will eventually convert to future reserves. Under both regimes, inferred resources, in particular, have a great amount of uncertainty as to their existence and their economic and legal feasibility. Investors are cautioned not to assume that any part or all of the inferred resource exists or is economically or legally mineable. See Item 1A, Risk Factors in the NioCorp Form 10-K. Reference should be made to the full text of the 2022 NI 43-101 Elk Creek Technical Report and the S-K 1300 Elk Creek Technical Report Summary for further information regarding the assumptions, qualifications and procedures relating to the estimates of mineral reserves and mineral resources as defined under NI 43-101 and S-K 1300, respectively.

QUESTIONS AND ANSWERS ABOUT THE TRANSACTIONS

The following questions and answers are intended to address briefly some commonly asked questions regarding the Transactions. These questions and answers may not address all questions that may be important to you. To better understand these matters, and for a description of the legal terms governing the Transactions, you should carefully read this entire joint proxy statement/prospectus, including the attached annexes, as well as the documents that have been incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find Additional Information” of this joint proxy statement/prospectus.

Why am I receiving this joint proxy statement/prospectus?

On September 25, 2022, NioCorp, GX and Merger Sub entered into the Business Combination Agreement. Pursuant to the Business Combination Agreement, among other transactions, the following transactions will occur: (i) Merger Sub will merge with and into GX, with GX surviving the merger, referred to as the First Merger; (ii) all GX Class A Shares that are held by GX Public Stockholders who have not elected to exercise their redemption rights in connection with the Transactions shall be converted into First Merger Class A Shares in GX, as the surviving company in the First Merger; (iii) NioCorp will purchase all First Merger Class A Shares in exchange for NioCorp Common Shares, referred to as the Exchange; (iv) NioCorp will assume the GX Warrant Agreement and each GX Warrant that was issued and outstanding immediately prior to the effective time of the Exchange will be converted into a NioCorp Assumed Warrant; (v) all of the First Merger Class A Shares will be contributed by NioCorp to Intermediate Holdco in exchange for additional shares of Intermediate Holdco, resulting in GX becoming a direct subsidiary of Intermediate Holdco; (vi) ECRC will merge with and into GX, with GX surviving the merger as a direct subsidiary of Intermediate Holdco, referred to as the Second Merger; and (vii) following the effective time of the Second Merger, each of NioCorp and GX, as the surviving company of the Second Merger, will effectuate the applicable reverse stock split. As a result of the Transactions, GX will become a subsidiary of NioCorp. In addition, pursuant to the Business Combination Agreement, the parties will enter into the Exchange Agreement, under which holders of 48,645,707 Second Merger Class B Shares (the “Vested Shares”) are entitled to exchange any or all of the Vested Shares for NioCorp Common Shares on a one-for-one basis, subject to certain equitable adjustments, in accordance with the terms of the Exchange Agreement, which are further described in Note 4 of the Notes to the Unaudited Pro Forma Condensed Combined Financial Information included elsewhere in this joint proxy statement/prospectus.

NioCorp will hold the NioCorp Shareholder Meeting and GX will hold the GX Stockholder Meeting to obtain these approvals and vote on other matters. You are receiving this joint proxy statement/prospectus in connection with the separate solicitations by (i) the NioCorp Board of proxies of NioCorp Shareholders in favor of the NioCorp Proposals and (ii) the GX Board of proxies of GX Stockholders in favor of the GX Proposals.

This joint proxy statement/prospectus constitutes a prospectus of NioCorp with respect to the NioCorp Common Shares and NioCorp Assumed Warrants issuable to GX Stockholders and GX warrant holders pursuant to the Business Combination Agreement. This joint proxy statement/prospectus also constitutes (i) a notice of meeting and management information and proxy circular of NioCorp with respect to the NioCorp Shareholder Meeting and (ii) a notice of meeting and a proxy statement of GX with respect to the GX Stockholder Meeting.

Your vote is very important. We encourage you to submit a proxy to have your NioCorp Common Shares or GX Common Stock voted as soon as possible.

What will GX Securityholders receive if the Transactions are completed?

Merger, each First Merger Class B Share shall be converted into 11.1829212 Second Merger Class B Shares of GX, as the surviving company in the Second Merger. Each Second Merger Class B Share will be exchangeable into NioCorp Common Shares on a one-for-one basis, subject to certain equitable adjustments, in accordance with the terms of the Exchange Agreement as further discussed in Note 4 of the Notes to the Unaudited Pro Forma Condensed Combined Financial Information.

Pursuant to the Business Combination Agreement, in connection with the First Merger and the assumption by NioCorp of the GX Warrant Agreement, each GX Warrant that is issued and outstanding immediately prior to the Exchange Time shall be converted into one NioCorp Assumed Warrant pursuant to the GX Warrant Agreement. Each NioCorp Assumed Warrant shall be exercisable solely for NioCorp Common Shares, and the number of NioCorp Common Shares subject to each NioCorp Assumed Warrant shall be equal to the number of shares of GX Common Stock subject to the applicable GX Warrant multiplied by 11.1829212, with the applicable exercise price to be adjusted accordingly.

Following the effective time of the Second Merger, NioCorp will effectuate a reverse stock split of the issued NioCorp Common Shares and GX will effectuate a reverse stock split of the Second Merger Class A Shares and Second Merger Class B Shares at a to-be-determined ratio.

Will NioCorp issue fractional shares in the Transactions?

No fractional NioCorp Common Shares will be issued pursuant to the Transactions. To the extent that the Transactions would result in any GX Stockholder being issued a fractional share, such fraction will be rounded down to the nearest whole share.

Do any of the directors or officers of NioCorp or GX have interests in the Transactions that may differ from or be in addition to my interests as a shareholder?

Except as disclosed in this joint proxy statement/prospectus, none of NioCorp’s directors or executive officers, nor any person who has held such a position since the beginning of NioCorp’s last completed financial year, nor any associate or affiliate of the foregoing persons, has any substantial or material interest, direct or indirect, by way of beneficial ownership of securities or otherwise, in the Transactions.

The GX Board and GX’s executive officers may have interests in the Business Combination that are different from, in addition to or in conflict with, yours. These interests include:

●

the beneficial ownership of the Sponsor and certain of GX’s directors and officers of an aggregate of 7,500,000 GX Founder Shares and 5,666,667 GX Founder Warrants, which shares and warrants would become worthless if GX does not complete a business combination by March 22, 2023 or obtain the approval of GX Stockholders to extend the deadline for GX to consummate its initial business combination, as the Sponsor and GX’s officers and directors have waived any redemption right with respect to these shares. The Sponsor paid an aggregate of $25,000 for its GX Founder Shares, and $8,500,000 for its GX Founder Warrants, and such shares and warrants have an aggregate market value of approximately $75,525,000 and $2,720,000, respectively, based on the closing price of GX Class A Shares of $10.07 and of GX Public Warrants of $0.48 on Nasdaq on January 24, 2023, the record date for the GX Stockholder Meeting. Each of GX’s officers and directors is a member of the Sponsor. Cooper Road, LLC (an entity controlled by Jay R. Bloom) and Dean C. Kehler are the managing members of the Sponsor, and as such Messrs. Bloom and Kehler have voting and investment discretion with respect to the GX Common Stock and GX Warrants held of record by the Sponsor;

●

the expected appointment of Messrs. Maselli and Kehler as directors of the Combined Company;

●

the fact that four of GX’s directors, Jay R. Bloom, Dean C. Kehler, Hillel Weinberger and Marc Mazur, served as directors of GX Acquisition Corp., a special purpose acquisition company that consummated its initial business combination with Celularity Inc. (the “Celularity Business Combination”) in July 2021;

●

the fact that GX’s Sponsor, officers and directors have agreed not to redeem any of their shares in connection with a stockholder vote to approve the Transactions;

●

the fact that the Sponsor and GX’s directors and officers will receive material benefits from the completion of an initial business combination and may be incentivized to complete the Transactions with NioCorp rather than liquidate (in which case the Sponsor would lose its entire investment), even if NioCorp is a less favorable target company or the terms of the Transactions are less favorable to GX Stockholders than an alternative transaction;

●

that, at the Closing, GX will enter into the Registration Rights and Lock-Up Agreement, which provides for registration rights to the Sponsor and its permitted transferees;

●

the continued indemnification of current directors and officers of GX and the continuation of directors’ and officers’ liability insurance after the completion of the Transactions;

●

the fact that the Sponsor (including its representatives and affiliates) and GX’s directors and officers, are, or may in the future become, affiliated with entities that are engaged in a similar business to GX. GX’s directors and officers also may become aware of business opportunities which may be appropriate for presentation to GX, and the other entities to which they owe certain fiduciary or contractual duties. Accordingly, they may have had conflicts of interest in determining to which entity a particular business opportunity should be presented. These conflicts may not be resolved in GX’s favor and such potential business opportunities may be presented to other entities prior to their presentation to GX, subject to applicable fiduciary duties under the General Corporation Law of the State of Delaware. The GX Existing Charter provides that GX renounces its interest in any corporate opportunity offered to any director or officer of GX unless such opportunity is expressly offered to such person solely in his or her capacity as a director or officer of GX and such opportunity is one GX is legally and contractually permitted to undertake and such person is legally permitted to refer such opportunity to GX. GX is not aware of any such conflict or opportunity being presented to any founder, director or officer of GX nor does GX believe that the limitation of the application of the “corporate opportunity” doctrine in the GX Existing Charter had any impact on its search for a potential business combination;

●

the fact that the Sponsor has invested an aggregate of $9,010,000 (consisting of $25,000 for the GX Founder Shares, $8,500,000 for the GX Founder Warrants, a $250,000 working capital loan and a second working capital loan for $235,000), which means the Sponsor, following the Transactions, may experience a positive rate of return on its investment, even if other GX Public Stockholders experience a negative rate of return on their investment;

●

the fact that the Sponsor is not expected to recognize taxable gain with respect to its GX Founder Shares at closing because it is retaining such shares pursuant to the Transactions (and not engaging in any taxable disposition). Rather, it will benefit from deferring any taxable gain until it ultimately exchanges its GX Founder Shares for NioCorp Common Shares (or cash); by contrast, the GX Public Stockholders generally are expected to recognize gain or loss upon exchanging their GX securities for NioCorp securities pursuant to the Transactions;

●

the fact that the Sponsor and GX’s officers and directors will be reimbursed for out-of-pocket expenses incurred in connection with activities on GX’s behalf, such as identifying potential target businesses and performing due diligence on suitable business combinations;

●

the fact that as of September 30, 2022, $20,000 was accrued and payable to Trimaran Fund Management, LLC, an affiliate of the Sponsor for monthly fees, and an additional $20,000 will be due and payable, monthly, until the consummation of the Transactions; and

●

the fact that the Sponsor and GX’s officers and directors will lose their entire investment in GX, a minimum of $9,010,000 in aggregate (consisting of $25,000 for 7,500,000 GX Founder Shares, $8,500,000 for the 5,666,667 GX Founder Warrants, the $250,000 amount outstanding under the working capital loan made by the Sponsor, the $235,000 amount outstanding under the second working capital loan made by the Sponsor, additional working capital loans made, out-of-pocket expenses to be repaid by GX and additional monthly fees due as noted above) if GX does not consummate an initial business combination by March 22, 2023 or, if approved by GX Stockholders by the extended deadline for GX to consummate its initial business combination.

These interests may influence GX’s directors in making their recommendation that you vote in favor of the approval of the Transactions. GX’s directors were aware of and considered these interests, among other matters, in evaluating the Transactions, and in recommending to GX Stockholders that they approve the Transactions. GX Stockholders should take these interests into account in deciding whether to approve the Transactions.

Is the obligation of each of NioCorp and GX to complete the Transactions subject to any conditions?

The consummation of the Transactions is subject to the satisfaction or waiver of certain customary closing conditions contained in the Business Combination Agreement, including, among other things, (i) obtaining required approvals of the Transactions and related matters by the respective shareholders of NioCorp and GX, (ii) the effectiveness of the registration statement of which this joint proxy statement/prospectus forms a part, (iii) receipt of approval for listing on Nasdaq of the NioCorp Common Shares to be issued in connection with the Transactions, (iv) receipt of approval for listing on Nasdaq of the NioCorp Assumed Warrants, (v) receipt of approval from the TSX with respect to the issuance and listing of the NioCorp Common Shares issuable in connection with the Transactions, (vi) that NioCorp and its subsidiaries (including GX, as the surviving company of the Second Merger) will have at least $5,000,001 of net tangible assets upon the consummation of the Transactions, after giving effect to any redemptions by GX Public Stockholders and after payment of underwriters’ fees or commissions, (vii) that, at Closing, NioCorp and its subsidiaries (including GX, as the surviving company of the Second Merger) will have received cash in an amount equal to or greater than $15,000,000, subject to certain adjustments (which amount may be satisfied with funds in the Trust Account or otherwise, as further described under “The Transactions—NioCorp’s Reasons for the Transactions and Recommendation of the NioCorp Board”) and (viii) the absence of any injunctions enjoining or prohibiting the consummation of the

Business Combination Agreement. Each of the foregoing conditions, in addition to the other customary conditions contained in the Business Combination Agreement, may be waived by the party or parties in whose favor such closing condition is made (to the extent permitted by applicable law), except that the first, second and eighth conditions listed above may not be waived pursuant to applicable law and the third and fourth conditions may not be waived without recirculation and resolicitation.

How will NioCorp Shareholders be affected by the Transactions?

NioCorp Shareholders will not be issued any additional NioCorp Common Shares in connection with the Transactions. As a result of the Transactions, NioCorp Shareholders will own shares in a larger company with more assets. However, because NioCorp will be issuing additional NioCorp Common Shares to GX Stockholders in exchange for their GX Class A Shares in connection with the Transactions, each NioCorp Common Share outstanding immediately prior to the Transactions will represent a smaller percentage of the aggregate number of NioCorp Common Shares issued and outstanding after the Transactions.

In addition, if the Transactions are consummated, NioCorp will assume the GX Warrant Agreement. An aggregate value of the outstanding NioCorp Assumed Warrants of approximately $7,520,000 (based on the closing price of the GX Public Warrants of $0.48 on the Nasdaq Global Market as of January 24, 2023, the record date for the GX Stockholders Meeting) may be retained by the redeeming stockholders assuming maximum redemptions. Any exercise of NioCorp Assumed Warrants after the completion of the Transactions will also result in dilution to NioCorp Shareholders.

Further, the Yorkville Financings also may result in potential dilution to NioCorp Shareholders. See the section entitled “Yorkville Financings.”

What happens if I sell or otherwise transfer my NioCorp Common Shares before the NioCorp Shareholder Meeting?

The record date for NioCorp Shareholders entitled to vote at the NioCorp Shareholder Meeting is February 1, 2023, which is earlier than the date of the NioCorp Shareholder Meeting. If you sell or otherwise transfer your shares after the record date but before the NioCorp Shareholder Meeting, unless special arrangements (such as provision of a proxy) are made between you and the person to whom you transfer your shares and each of you notifies NioCorp in writing of such special arrangements, you will retain your right to vote such shares at the NioCorp Shareholder Meeting but will otherwise transfer ownership of and the economic interest in your NioCorp Common Shares.

Who will be the officers and directors of NioCorp if the Transactions are consummated?

Following the Closing, it is anticipated that current officers and directors of NioCorp will remain in such roles and that Messrs. Maselli and Kehler will be appointed to the NioCorp Board.

If I sell my GX Class A Shares shortly before the completion of the Transactions, will I still be entitled to receive NioCorp Common Shares?

No. In order to receive the NioCorp Common Shares upon completion of the Transactions, you must hold your GX Class A Shares through the effective time of the Transactions.

Do you expect the Transactions to be taxable to me?

The parties generally expect that a U.S. or Canadian holder of GX Class A Shares or GX Warrants will be subject to U.S. or Canadian federal income tax, respectively, with respect to any gain resulting from such holder’s exchange of GX Class A Shares or GX Warrants in the Transactions. For a more complete description of the tax consequences of the Transactions, please see the sections entitled “Material U.S. Federal Income Tax Considerations—Material U.S. Federal Income Tax Considerations With Respect to the Redemption and the Transactions” and “Material Canadian Federal Income Tax Considerations—Material Canadian Federal Income Tax Considerations for Existing Holders of GX Securities.”

Are there risks associated with the Transactions?

Yes, there are important risks involved. Before making any decision on whether and how to vote, you are urged to read carefully and in its entirety, the section entitled “Risk Factors” beginning on page [●] of this joint proxy statement/prospectus and in any documents incorporated by reference into this joint proxy statement/prospectus.

Have the directors of NioCorp and GX considered the fairness of the Transactions?

Yes, the NioCorp Board and the GX Board have separately (a) determined that the Transactions are fair to the NioCorp Shareholders and that the Transactions and entry into the Business Combination Agreement and the Ancillary Agreements are in the best interests of NioCorp, and that the business combination and the Transactions are advisable, fair to, and in the best interests of GX and the GX Stockholders, as applicable, (b) approved the Business Combination Agreement and the Transactions and declared their advisability, and (c) recommended that the NioCorp Shareholders and GX Stockholders approve and adopt the NioCorp Proposals and the GX Proposals, as applicable, in order to effectuate the Transactions.

GenCap Mining Advisory Ltd. (“GenCap”) has provided a fairness opinion to the NioCorp Board stating that, as of the date of such opinion, and based upon and subject to the assumptions, limitations, and qualifications stated in such opinion, the Transactions are fair, from a financial point of view, to NioCorp Shareholders.

Scalar, LLC (“Scalar”) has provided a fairness opinion to the GX Board stating that, as of the date of such opinion, and based upon and subject to the assumptions, limitations and qualifications stated in such opinion, the consideration to be received by the holders of the GX Class A Shares is fair from a financial point of view to such shareholders.

Will NioCorp obtain new financing in connection with the Transactions?

On January 26, 2023, NioCorp entered into definitive agreements for two separate financing packages with Yorkville. These financings could provide NioCorp with access to up to an additional $80,360,000, before related fees and expenses payable by NioCorp, to help advance the Elk Creek Project, which NioCorp can use whether or not there are redemptions by GX Public Stockholders. The financings contemplated by the Yorkville Financing Agreements include $16 million in convertible debentures that are expected to be funded at Closing and a standby equity purchase facility pursuant to which NioCorp will have the ability to require Yorkville, subject to the conditions set out in the Yorkville Equity Facility Financing Agreement, to purchase up to $65 million of NioCorp Common Shares. The closing of any transactions contemplated by the Yorkville Financing Agreements is not a condition to closing the Transactions; however, the failure to consummate the Yorkville Financings may impact the ability of NioCorp and GX to close the Transactions. See “Risk Factors—Risks Related to GX and the Transactions—If NioCorp fails to consummate the Yorkville Financings, it is possible that the Transactions may not be completed.”

In addition, pursuant to the terms of the Yorkville Convertible Debt Financing Agreement, in the event that the First Debenture Closing (as defined below under the heading “Yorkville Financings—Yorkville Convertible Debt Financing”) does not occur on or prior to March 22, 2023, an Investor (as defined below under the heading “Yorkville Financings—Yorkville Convertible Debt Financing”) will have the right to terminate the Yorkville Convertible Debt Financing Agreement with respect to itself until 11:59 p.m. on March 27, 2023. If an Investor does not exercise its right to terminate the Yorkville Convertible Debt Financing Agreement by such time, then the Yorkville Convertible Debt Financing Agreement will be automatically extended for 30 days, following which the Investor will have the right to terminate the Yorkville Convertible Debt Financing Agreement with respect to itself until 11:59 p.m. on the date that is five days following such 30-day period. The Yorkville Convertible Debt Financing Agreement will continue to be automatically extended for subsequent 30-day periods, in each case following five-day periods in which the Investor may exercise its right to terminate the Yorkville Convertible Debt Financing Agreement with respect to itself.

NioCorp may terminate the Yorkville Convertible Debt Financing Agreement at any time prior to the First Debenture Closing for any reason and in its sole discretion; provided that if it exercises this right, NioCorp will be required to pay a cash termination fee of $1,600,000 to the Investors, on a pro rata basis.

The Yorkville Convertible Debt Financing Agreement will terminate automatically if the Business Combination Agreement is terminated. For the avoidance of doubt, the $1,600,000 termination fee will not be payable if the Yorkville Convertible Debt Financing Agreement terminates pursuant to its terms upon the termination of the Business Combination Agreement.

The Yorkville Equity Facility Financing Agreement will terminate automatically following the expiration of the Commitment Period (as defined below under the heading “Yorkville Financings—Yorkville Convertible Debt Financing”). In addition, the Yorkville Equity Facility Financing Agreement will terminate automatically if the Business Combination Agreement is terminated.

NioCorp may terminate the Yorkville Equity Facility Financing Agreement effective upon five trading days’ prior written notice to Yorkville, as long as there are no outstanding unsettled rights to sell NioCorp Common Shares under the Equity Facility and NioCorp has paid all amounts owed to Yorkville under the Yorkville Equity Facility Financing Agreement, including, without limitation, any unpaid portion of the aggregate cash fee of $1,500,000 payable in installments under the Yorkville Equity Facility Financing Agreement.

The parties may also terminate the Yorkville Equity Facility Financing Agreement by mutual written consent.

NioCorp cannot complete the Yorkville Financings if the Yorkville Equity Facility Financing Proposal and the Yorkville Convertible Debt Financing Proposal are not approved at the NioCorp Shareholder Meeting.

Do NioCorp Shareholders or GX Stockholders have appraisal or dissenter’s rights in connection with the Transactions?

There are no appraisal or dissenter’s rights available to NioCorp Shareholders or GX Stockholders in connection with the Transactions.

What is the Sponsor’s ownership interest in the Combined Company immediately after the consummation of the Transactions?

Assuming the no redemption scenario, the Sponsor would own 7.1% or 11.7% of the Combined Company, and assuming the maximum redemption scenario, the Sponsor would own 14.3% or 22.2% of the Combined Company, excluding the Earnout Shares or including the Earnout Shares, respectively. The value of such shares on an as-converted basis proforma for the Transactions and based on the trading price of NioCorp stock of $0.82 per share is $39.1 million excluding the Earnout Shares and $67.1 million including the Earnout Shares. This compares to a price paid of $25,000 for the GX Founder Shares and $8,500,000 for the GX Founder Warrants.

However, on a fully diluted basis, including the shares issued to Cantor and BTIG in connection with their fee arrangements as part of the Transactions and assuming all dilutive securities are treated on an as-converted basis, including the GX Warrants, the outstanding options, warrants and convertible notes of NioCorp and the anticipated NioCorp Debentures and NioCorp Financing Warrants, assuming the no redemption scenario, the Sponsor would own 12.2% or 15.34% of the Combined Company, and assuming the maximum redemption scenario, the Sponsor would own 19.1% or 23.7% of the Combined Company, excluding the Earnout Shares or including the Earnout Shares, respectively. The value of such shares on an as-converted basis proforma for the Transactions and based on the trading price of NioCorp stock of $0.82 per share is $39.1 million excluding the Earnout Shares and $67.1 million including the Earnout Shares. This compares to a price paid of $25,000 for the GX Founder Shares. In addition, based on a price of $0.78 per warrant, the value of the GX Founder Warrants, is $4.4 million. This compares to a price paid of $25,000 for the GX Founder Shares and $8.5 million for the GX Founder Warrants.

	No Redemptions of Public Shares			Maximum Redemptions of Public Shares
	Number of NioCorp Common Shares	Percentage of total number of NioCorp Common Shares		Number of NioCorp Common Shares	Percentage of total number of NioCorp Common Shares
*(1) No Dilution – Without Earnout:*
NioCorp Common Shares held by the Sponsor	47,650,427	7.1	%⁽¹⁾	47,650,427	14.3	%⁽²⁾

*(2) No Dilution – With Earnout:*
NioCorp Common Shares held by the Sponsor	81,881,347	11.7	%⁽³⁾	81,881,347	22.2	%⁽⁴⁾

*(3) Fully Diluted – Without Earnout:*
NioCorp Common Shares held by the Sponsor	47,650,427	5.2	%⁽⁵⁾	47,650,427	8.2	%⁽⁶⁾
NioCorp Common Shares underlying NioCorp Assumed Warrants held by the Sponsor	63,369,890	6.9	%⁽⁵⁾	63,369,890	10.9	%⁽⁶⁾
Total	111,020,317	12.2	%⁽⁵⁾	111,020,317	19.1	%⁽⁶⁾

*(4) Fully Diluted – With Earnout:*
NioCorp Common Shares held by the Sponsor	81,881,347	8.6	%⁽⁷⁾	81,881,347	13.3	%⁽⁸⁾
NioCorp Common Shares underlying NioCorp Assumed Warrants held by the Sponsor	63,369,890	6.7	%⁽⁷⁾	63,369,890	10.3	%⁽⁸⁾
Total	145,251,237	15.3	%⁽⁷⁾	145,251,237	23.7	%⁽⁸⁾

(1)

Percentages calculated over a total of 667,300,864 NioCorp Common Shares. Figures have been rounded for ease of presentation.

(2)

(3)

Percentages calculated over a total of 701,531,784 NioCorp Common Shares. Figures have been rounded for ease of presentation.

(4)

(5)

Percentages calculated over a total of 667,300,864 NioCorp Common Shares plus 245,686,058 NioCorp Common Shares issued from the exercise of the GX Warrants, the options, warrants and outstanding convertible securities of NioCorp and the Yorkville Financings. Figures have been rounded for ease of presentation.

(6)

Percentages calculated over a total of 334,161,641 NioCorp Common Shares, based on a reduction of 29,790,000 GX Class A Shares (converted to NioCorp Common Shares at the exchange ratio) subject to possible redemption, plus 245,686,058 NioCorp Common Shares issued from the exercise of the GX Warrants, the options, warrants and outstanding convertible securities of NioCorp and the Yorkville Financings. Figures have been rounded for ease of presentation.

(7)

Percentages calculated over a total of 701,531,784 NioCorp Common Shares plus 245,686,058 NioCorp Common Shares issued from the exercise of the GX Warrants, the options, warrants and outstanding convertible securities of NioCorp and the Yorkville Financings. Figures have been rounded for ease of presentation.

(8)

Percentages calculated over a total of 368,392,561 NioCorp Common Shares, based on a reduction of 29,790,000 GX Class A Shares (converted to NioCorp Common Shares at the exchange ratio) subject to possible redemption, plus 245,686,058 NioCorp Common Shares issued from the exercise of the GX Warrants, the options, warrants and outstanding convertible securities of NioCorp and the Yorkville Financings. Figures have been rounded for ease of presentation.

When will the Transactions be completed?

NioCorp and GX are working to complete the Transactions as quickly as possible. Assuming that the Share Issuance Proposal, the Quorum Amendment Proposal, the Business Combination Proposal, the Charter Amendment Proposal and the Charter Proposal are approved by the NioCorp Shareholders and the GX Stockholders, as applicable, other important conditions to the closing of the Transactions exist. Assuming the satisfaction of all necessary closing conditions, the

parties to the Business Combination Agreement expect to complete the Transactions during the first quarter of 2023. For a discussion of the conditions to the completion of the Transactions, see the section entitled “The Business Combination Agreement — Conditions to the Transactions” of this joint proxy statement/prospectus.

What happens if the Transactions are not completed?

If the Transactions are not completed for any reason, GX Stockholders will not receive any consideration for their GX Class A Shares, GX will remain an independent public company with GX Class A Shares being traded on the Nasdaq Capital Market and NioCorp will remain an independent public company with NioCorp Common Shares being traded on the TSX.

If, as a result of the termination of the Business Combination Agreement or otherwise, GX is unable to complete a business combination by March 22, 2023 or obtain the approval of GX Stockholders to extend the deadline for GX to consummate an initial business combination, the GX Existing Charter provides that GX will: (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten business days thereafter subject to lawfully available funds therefor, redeem 100% of the outstanding GX Class A Shares in consideration of a per-share price, payable in cash, equal to the quotient obtained by dividing (A) the aggregate amount then on deposit in the Trust Account, including interest not previously released to GX to pay its taxes (less up to $100,000 of such net interest to pay dissolution expenses), by (B) the total number of then outstanding GX Class A Shares, which redemption will completely extinguish rights of the GX Public Stockholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the remaining GX Stockholders and the GX Board in accordance with applicable law, dissolve and liquidate, subject in each case to GX’s obligations under the DGCL to provide for claims of creditors and other requirements of applicable law. See the sections of this joint proxy statement/prospectus entitled “Risk Factors — Risks Relating to GX and the Transactions — GX may not be able to complete an initial business combination within the prescribed time frame, in which case it would cease all operations except for the purpose of winding up and it would redeem the GX Class A Shares and liquidate, in which case the GX Public Stockholders may only receive $10.00 per share plus accrued interest in trust, or less than such amount in certain circumstances, and the GX Public Warrants will expire worthless” and “— GX stockholders may be held liable for claims by third parties against GX to the extent of distributions received by them upon redemption of their shares.” GX’s Sponsor, officers and directors have waived any right to any liquidation distribution with respect to those shares.

In the event of liquidation, there will be no distribution with respect to outstanding GX Warrants. Accordingly, the GX Warrants will expire worthless.

What voting and equity interests will NioCorp have in GX as a result of the Transactions and what are the rights of the holders of the GX Class B common stock in GX?

Following the Closing, GX will become an indirect subsidiary of NioCorp. As a result of the Transactions and immediately following the Closing, the issued and outstanding common stock of GX will consist of certain Second Merger Class A Shares held by NioCorp and certain Second Merger Class B Shares held by the Sponsor. Assuming no Second Merger Class B Shares held by the Sponsor are exchanged, the post-closing equity interest of GX will be held by the following holders as shown in the table below assuming no redemption or maximum redemption scenarios and excluding or including the Earnout Shares (as defined below):

	No Redemptions	Maximum Redemption
Shareholder	Ownership and Voting Interest	Ownership and Voting Interest
Excluding Earnout Shares:
NioCorp	92.9%	85.7%
Sponsor	7.1%	14.3%

Including Earnout Shares:
NioCorp	88.3%	77.8%
Sponsor	11.7%	22.2%

The Sponsor will be entitled to exchange any or all of its shares of Second Merger Class B Shares in GX (subject, in the case of Earnout Shares, to becoming Released Earnout Shares, as described below) for NioCorp Common Shares on a one-for-one basis, subject to certain equitable adjustments, in accordance with the terms of the Exchange Agreement. Under certain circumstances, and subject to certain exceptions, NioCorp may instead settle all or a portion of any exchange pursuant to the terms of the Exchange Agreement in cash, in lieu of NioCorp Common Shares, based on a volume-weighted average price of NioCorp Common Shares.

At Closing, the Sponsor will be entitled to exchange 47,650,427 Second Merger Class B Shares (the “Vested Shares”) for NioCorp Common Shares, while 34,230,920 of the Second Merger Class B Shares (the “Earnout Shares”) held by the Sponsor will be subject to vesting during the first ten years following the business combination. Such Earnout Shares vest in two equal tranches and are issuable to the holders based upon achieving market share price milestones of $13.42 per share divided by the Exchange Ratio and $16.77 per share divided by the Exchange Ratio within a period of ten years post-recapitalization, or upon a change in control as defined in the GX Support Agreement. These shares will be forfeited if the market share price milestones or an acceleration event is not reached within the ten-year period. At such time that the Earnout Shares shall become vested (the “Released Earnout Shares”), the Released Earnout Shares may be exchanged by the holders for NioCorp Common Shares at any time. Under the Exchange Agreement, all Vested Shares and Earnout Shares must be exchanged for NioCorp Common Shares by the tenth anniversary of the closing date (the “Ten Year Anniversary”) except for Released Earnout Shares that have been vested for a period of fewer than twenty-four months as of the Ten Year Anniversary. The exchange right with respect to such Released Earnout Shares will expire on the date that is twenty-four months after the vesting date.

A holder of an Earnout Share shall not be entitled to receive dividends or other distributions made by GX or NioCorp before such Earnout Share becomes Released Earnout Shares. A holder of a Vested Share or a Released Earnout Share shall be entitled to receive such holder’s portion of any dividends or other distributions made by (i) GX to its holders of common stock and (ii) NioCorp to its holders of common stock on an as-exchanged (pursuant to the Exchange Agreement) to NioCorp Common Shares basis (subject to the terms of the GX Proposed Charter).

In addition, following the consummation of the Transactions, the issued and outstanding common stock of GX will have differentiated voting rights with respect to Second Merger Class A Shares and Second Merger Class B Shares. The holders of GX common stock will have all voting power with respect to GX, except that the holders of Second Merger Class A Shares will have the exclusive right to vote for the election and removal of directors. Please see the section entitled “GX Proposal No. 3 Through No. 9 — The Charter Proposal” for a more complete description of the voting rights of the holders of GX Common Stock.

QUESTIONS AND ANSWERS ABOUT THE NIOCORP SHAREHOLDER MEETING

Why am I receiving these materials?

The NioCorp Board is making these materials available to you in connection with the NioCorp Shareholder Meeting to be held , 2023. As a NioCorp Shareholder, you are invited to attend the NioCorp Shareholder Meeting and are entitled and requested to vote on the business items described in this joint proxy statement/prospectus. This joint proxy statement/prospectus is furnished in connection with the solicitation of proxies by or on behalf of the management and the NioCorp Board. This joint proxy statement/prospectus is designed to assist you in voting your shares and includes information that NioCorp is required to provide under the rules of the SEC and applicable Canadian securities laws.

Who is entitled to vote at the NioCorp Shareholder Meeting?

The record date for determining NioCorp Shareholders entitled to receive notice of and vote at the NioCorp Shareholder Meeting is February 1, 2023. Persons who are registered NioCorp Shareholders at the close of business on February 1, 2023 will be entitled to receive notice of and vote at the NioCorp Shareholder Meeting. By ballot, every NioCorp Shareholder and proxyholder will have one vote for each NioCorp Common Share.

How can I vote?

The answer depends on whether you are a registered shareholder or a beneficial shareholder.

If you are a registered shareholder, you own your NioCorp Common Shares directly (that is, you hold shares that show your name as the registered shareholder). Your proxy is being solicited directly by the NioCorp Board and you may vote at the NioCorp Shareholder Meeting or by proxy whether or not you attend the NioCorp Shareholder Meeting.

In order for a proxy to be valid, it must be:

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signed by the registered shareholder whose name appears thereon or by such registered shareholder’s attorney authorized in writing, or if the registered shareholder is a corporation, by a duly authorized representative on behalf of such corporation; and

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returned in one of the following manners:

by hand delivery or by mail addressed to Computershare Investor Services Inc., Proxy Dept., 100 University Avenue, 8th Floor, Toronto, Ontario, M5J 2Y1, and received by , Mountain time, on , 2023, or no later than 48 hours before the NioCorp Shareholder Meeting is reconvened following any adjournment or postponement;

by facsimile to Computershare Investor Services Inc. at 1-866-249-7775 (within North America) or

1-416-263-9524 (outside North America) and received by , Mountain time, on , 2023, or no later than 48 hours before the NioCorp Shareholder Meeting is reconvened following any adjournment or postponement; or

by deposit with the chair of the NioCorp Shareholder Meeting prior to commencement of the NioCorp Shareholder Meeting.

An executed proxy that is returned undated will be deemed to be dated the date of the mailing of the form of proxy by NioCorp or its agent.

Alternatively, a registered shareholder may vote via the Internet or by telephone by following the instructions included in the NioCorp Meeting Materials, in each case no later than , Mountain time, on , 2023, or no later than 48 hours before the NioCorp Shareholder

Meeting is reconvened following any adjournment or postponement. All instructions for how to vote are also listed in the accompanying form of proxy and notes thereto.

If you are a beneficial shareholder, you own your NioCorp Common Shares indirectly (that is, you hold your shares in “street name” in a brokerage account or by another nominee holder). NioCorp Common Shares held by brokers, agents,

trustees or other intermediaries can only be voted by those brokers, agents, trustees or other intermediaries in accordance with instructions received from beneficial shareholders. As a result, beneficial shareholders should carefully review the voting instructions provided by their intermediary with this joint proxy statement/prospectus and ensure they communicate how they would like their NioCorp Common Shares voted in accordance with those instructions.

Intermediaries will frequently use service companies to forward proxy solicitation information to Beneficial Shareholders. Generally, a Beneficial Shareholder who has not waived the right to receive such information will either:

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be given a form of proxy which (i) has already been signed by the intermediary (typically by a facsimile, stamped signature), (ii) is restricted as to the number of shares beneficially owned by the beneficial shareholder, and (iii) must be completed, but not signed, by the beneficial shareholder and deposited with Computershare Investor Services Inc.; or

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more typically, be given a voting instruction form, which (i) is not signed by the intermediary, and (ii) when properly completed and signed by the beneficial shareholder and returned to the intermediary or its service company, will constitute voting instructions which the intermediary must follow.

Voting instruction forms should be completed and returned in accordance with the specific instructions noted on the voting instruction form.

How will proxies be exercised?

The persons named in the accompanying form of proxy will vote the NioCorp Common Shares represented by the proxy in accordance with your instructions, provided your instructions are clear. The form of proxy gives the persons named as proxy holders discretionary authority regarding amendments or variations to matters identified therein and any other matter that may properly come before the NioCorp Shareholder Meeting.

If no instruction as to how to vote is given in an executed, duly returned and not revoked proxy appointing one of the management nominees named in a form of proxy, the proxy will be voted “FOR” each of the NioCorp Proposals.

Can I change my vote or revoke my proxy?

Yes, you may revoke your proxy at any time before it is exercised. If you are a registered shareholder who has returned a valid proxy or voting instructions, you may revoke your proxy at any time by signing a proxy bearing a later date, signing a written notice of revocation in the same manner as the form of proxy is required to be signed as set out in the notes to the proxy, or in any other manner permitted by law.

The later proxy or the notice of revocation must be delivered to the office of NioCorp’s registrar and transfer agent or to NioCorp’s principle executive offices at any time up to and including the last business day before the scheduled time of the NioCorp Shareholder Meeting or the reconvening of the NioCorp Shareholder Meeting following any adjournment, or to the chair of the NioCorp Shareholder Meeting on the day of the NioCorp Shareholder Meeting or the reconvening of the NioCorp Shareholder Meeting following any adjournment.

You may also revoke your proxy or voting instructions by voting via Internet or telephone at a later date than the date of the proxy, or by attending the NioCorp Shareholder Meeting and voting in person.

If you are a non-registered shareholder who wishes to revoke a voting instruction form or to revoke a waiver of your right to receive NioCorp Meeting Materials and to give voting instructions, you must give written instructions to your broker, agent, trustee or other intermediary through which you hold your NioCorp Common Shares in accordance with the applicable procedures and deadlines of your broker, agent, trustee or other intermediary.

How many shares must be present or represented to conduct business at the NioCorp Shareholder Meeting?

Under the NioCorp Articles, a quorum for the transaction of business at the NioCorp Shareholder Meeting is one or more persons present and being, or representing by proxy, two or more shareholders entitled to attend and vote at the NioCorp Shareholder Meeting.

Broker non-votes will not be counted as present for purposes of determining the presence of a quorum for purposes at the NioCorp Shareholder Meeting and will not be voted. If a quorum is not present, the NioCorp Shareholder Meeting will be adjourned until a quorum is obtained.

What am I being asked to vote on and what vote is required to approve each proposal?

NioCorp Proposal No. 1 — To approve the issuance of NioCorp Common Shares to GX Stockholders in connection with the Transactions and the possible creation of Sponsor as a control person (the “Share Issuance Proposal”).

Assuming a quorum is present at the NioCorp Shareholder Meeting, approval of the Share Issuance Proposal requires the affirmative vote of a simple majority of the votes cast, either in person or by proxy, at the NioCorp Shareholder Meeting. Failures to vote will not be counted “FOR” or “AGAINST” the Share Issuance Proposal and will have no effect on the outcome of the proposal. If a NioCorp Shareholder does not specify a choice in the accompanying form of proxy and the NioCorp Shareholder has appointed one of the management nominees named in the form of proxy, the management nominee will vote NioCorp Common Shares represented by the proxy “FOR” the Share Issuance Proposal.

NioCorp Proposal No. 2 — To approve the issuance of all of the NioCorp Common Shares that may be issuable upon a sale at the Purchase Price, and all of the Commitment Shares to be issued, in each case, in connection with the transactions contemplated by the Yorkville Equity Facility Financing Agreement (the “Yorkville Equity Facility Financing Proposal”).

Assuming a quorum is present at the NioCorp Shareholder Meeting, approval of the Yorkville Equity Facility Financing Proposal requires the affirmative vote of a simple majority of the votes cast, either in person or by proxy, at the NioCorp Shareholder Meeting. Failures to vote will not be counted “FOR” or “AGAINST” the Yorkville Equity Facility Financing Proposal and will have no effect on the outcome of the proposal. If a NioCorp Shareholder does not specify a choice in the accompanying form of proxy and the NioCorp Shareholder has appointed one of the management nominees named in the form of proxy, the management nominee will vote NioCorp Common Shares represented by the proxy “FOR” the Yorkville Equity Facility Financing Proposal.

NioCorp is also seeking approval of the Yorkville Equity Facility Financing Proposal by the NioCorp Shareholders at the NioCorp Shareholder Meeting for purposes of Nasdaq Listing Rules 5635(b) and 5635(d) and Section 607(g) of the TSX Company Manual. See “NioCorp Proposal No. 2 – The Yorkville Equity Facility Financing Proposal” for more information about the requirements under Nasdaq Listing Rules 5635(b) and 5635(d) and Section 607(g) of the TSX Company Manual. Approval of the Yorkville Equity Facility Financing Proposal will constitute shareholder approval of such proposal for purposes of Nasdaq Listing Rules 5635(b) and 5635(d) and Section 607(g) of the TSX Company Manual.

NioCorp Proposal No. 3 — To approve the issuance of all of the NioCorp Convertible Debentures that may be issuable, all of the NioCorp Financing Warrants that may be issuable, and all of the NioCorp Common Shares that may be issuable upon conversion of the principal amount of, and any and all accrued interest on, the NioCorp Convertible Debentures at the Conversion Price and upon exercise of the NioCorp Financing Warrants, in each case, in connection with the transactions contemplated by the Yorkville Convertible Debt Financing Agreement (the “Yorkville Convertible Debt Financing Proposal”).

Assuming a quorum is present at the NioCorp Shareholder Meeting, approval of the Yorkville Convertible Debt Financing Proposal requires the affirmative vote of a simple majority of the votes cast, either in person or by proxy, at the NioCorp Shareholder Meeting. Failures to vote will not be counted “FOR” or “AGAINST” the Yorkville Convertible Debt Financing Proposal and will have no effect on the outcome of the proposal. If a NioCorp Shareholder does not specify a choice in the accompanying form of proxy and the NioCorp Shareholder has appointed one of the management nominees named in the form of proxy, the management nominee will vote NioCorp Common Shares represented by the proxy “FOR” the Yorkville Convertible Debt Financing Proposal.

NioCorp is also seeking approval of the Yorkville Convertible Debt Financing Proposal by the NioCorp Shareholders at the NioCorp Shareholder Meeting for purposes of Nasdaq Listing Rules 5635(b) and 5635(d) and Section 607(g) of the TSX Company Manual. See “NioCorp Proposal No. 3 – The Yorkville Convertible Debt Financing Proposal” for more information about the requirements under Nasdaq Listing Rules 5635(b) and 5635(d) and Section 607(g) of the TSX Company Manual. Approval of the Yorkville Convertible Debt Financing Proposal will constitute shareholder approval of such proposal for purposes of Nasdaq Listing Rules 5635(b) and 5635(d) and Section 607(g) of the TSX Company Manual.

NioCorp Proposal No. 4 — To approve, with or without amendment, an amendment to the NioCorp Articles in connection with the Transactions (the “Quorum Amendment Proposal”), the form of which amendment is attached as Annex B to this joint proxy statement/prospectus.

Assuming a quorum is present at the NioCorp Shareholder Meeting, approval of the Quorum Amendment Proposal requires the affirmative vote of a simple majority of the votes cast, either in person or by proxy, at the NioCorp Shareholder Meeting. Failures to vote will not be counted “FOR” or “AGAINST” the Quorum Amendment Proposal and will have no effect on the outcome of the proposal. If a NioCorp Shareholder does not specify a choice in the accompanying form of proxy and the NioCorp Shareholder has appointed one of the management nominees named in the form of proxy, the management nominee will vote NioCorp Common Shares represented by the proxy “FOR” the Quorum Amendment Proposal.

NioCorp Proposal No. 5— To approve, a proposal to adjourn the NioCorp Shareholder Meeting to a later date or dates, if necessary, to permit further solicitation and vote of proxies if, based upon the tabulated vote at the time of the NioCorp Shareholder Meeting, there are not sufficient votes to approve one or more proposals presented to stockholders for vote (the “Adjournment Proposal”).

Assuming a quorum is present at the NioCorp Shareholder Meeting, approval of the Adjournment Proposal requires the affirmative vote of a simple majority of the votes cast, either in person or by proxy, at the NioCorp Shareholder Meeting. Failures to vote will not be counted “FOR” or “AGAINST” the Adjournment Proposal and will have no effect on the outcome of the proposal. If a NioCorp Shareholder does not specify a choice in the accompanying form of proxy and the NioCorp Shareholder has appointed one of the management nominees named in the form of proxy, the management nominee will vote NioCorp Common Shares represented by the proxy “FOR” the Adjournment Proposal.

What do NioCorp Shareholders need to do now?

NioCorp urges you to read this joint proxy statement/prospectus carefully, including the attached annexes, as well as the documents that have been incorporated by reference into this joint proxy statement/prospectus. We encourage you to submit a proxy to have your NioCorp Common Shares voted as soon as possible.

As a NioCorp Shareholder, how does the NioCorp Board recommend that I vote?

After careful consideration, including a review of the opinion of GenCap Mining Advisory Ltd., information concerning GX, the Business Combination Agreement, proposed Transactions and alternatives, and consultation with management and NioCorp’s financial advisors and legal counsel, and consideration of such other matters as the NioCorp Board considered relevant, the NioCorp Board has unanimously resolved (i) that the Transactions are fair to the NioCorp Shareholders and (ii) that the Transactions and entering into of the Business Combination Agreement and the other ancillaries contemplated thereby are in the best interests of NioCorp . The NioCorp Board unanimously recommends that NioCorp Shareholders vote:

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NioCorp Proposal No. 1: “FOR” the Share Issuance Proposal;

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NioCorp Proposal No. 2: “FOR” the Yorkville Equity Facility Financing Proposal;

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NioCorp Proposal No. 3: “FOR” the Yorkville Convertible Debt Financing Proposal;

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NioCorp Proposal No. 4: “FOR” the Quorum Amendment Proposal; and

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NioCorp Proposal No. 5: “FOR” the Adjournment Proposal.

Did the NioCorp Board receive a fairness opinion in connection with the Transactions?

Yes. On September 25, 2022, GenCap Mining Advisory Ltd. rendered its oral opinion to the NioCorp Board (which was subsequently confirmed in writing by delivery of a written opinion dated September 25, 2022) to the effect that, subject to the assumptions, qualifications, limitations and other matters considered by GenCap in connection with the preparation of its opinion, as of such date, the Transactions are fair, from a financial point of view, to the NioCorp Shareholders. See “The Transactions — GX’s Reasons for the Transactions and Recommendation of the GX Board — Opinion of NioCorp’s Financial Advisor” and Annex E in this joint proxy statement/prospectus.

The full text of the written opinion of GenCap Mining Advisory Ltd., dated September 25, 2022, is attached as Annex E to this joint proxy statement/prospectus. The summary of the opinion provided in this joint proxy statement/prospectus is qualified in its entirety by reference to the full text of GenCap Mining Advisory Ltd.’s written opinion. GenCap Mining Advisory Ltd.’s advisory services and opinion were provided for the information and assistance of the NioCorp Board in connection with its consideration of the Transactions and the opinion does not constitute a recommendation as to how any NioCorp Shareholder should vote with respect to any of the NioCorp Proposals or any other matter.

How can I find out the results of the NioCorp Shareholder Meeting?

Preliminary voting results will be announced at the NioCorp Shareholder Meeting. Final voting results will be filed with the securities commissions or equivalent securities regulatory authority in each of the Provinces of British Columbia, Alberta, Saskatchewan, Ontario and New Brunswick, and on SEDAR at www.sedar.com, and will also be published in a Current Report on Form 8-K filed with the SEC on EDGAR at www.sec.gov within four business days of the NioCorp Shareholder Meeting.

QUESTIONS AND ANSWERS ABOUT THE GX STOCKHOLDER MEETING

Why is GX proposing the Business Combination Proposal?

GX was organized for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses. GX is not limited to any particular industry or sector.

GX received $300,000,000 from its IPO and sale of the GX Founder Warrants, which was placed into the Trust Account immediately following the IPO. In accordance with the GX Existing Charter, the funds held in the Trust Account will be released upon the consummation of the Transactions. See the question entitled “What happens to the funds held in the Trust Account upon consummation of the Business Combination?”

There currently are 30,000,000 GX Class A Shares issued and outstanding and 7,500,000 GX Founder Shares outstanding. In addition, there currently are 15,666,667 GX Warrants issued and outstanding, consisting of 10,000,000 GX Public Warrants and 5,666,667 GX Founder Warrants. Each whole GX Warrant entitles the holder thereof to purchase one GX Class A Share at a price of $11.50 per share. The GX Public Warrants will become exercisable 30 days after the completion of a business combination, and expire at 5:00 p.m., New York City time, five years after the completion of a business combination or earlier upon redemption or liquidation. The GX Founder Warrants, however, are non-redeemable so long as they are held by their initial purchasers or their permitted transferees.

Under the GX Existing Charter, GX must provide all holders of GX Class A Shares with the opportunity to have their GX Class A Shares redeemed upon the consummation of GX’s initial business combination in conjunction with a stockholder vote.

NioCorp’s Elk Creek Project is a pure play critical minerals project with the highest grade niobium resource in North America and the second largest indicated rare earth resource in the United States. Based on due diligence investigations into NioCorp, GX believes NioCorp is well positioned to be a reliable, U.S.-based supplier that will produce these critical minerals in an environmentally superior manner, with its expected mining operations designed from the start with sustainability in mind. NioCorp’s mission is to accelerate the global transition to a lower carbon economy. Further, NioCorp’s Elk Creek Project is guided by the Equator Principles environmental, social and governance (“ESG”) framework and incorporates recycling, water conservation and many other sustainability strategies. GX believes that NioCorp will be able to produce minerals in an environmentally superior manner as the mine and processing plant are designed to have 100% process water recycling, reagent recycling, ground freezing to protect groundwater resources and that the tailings are used for mine backfill. GX believes this is superior as the mine could have been designed without such attributes. NioCorp also has a strong focus on sustainability as it has developed and deployed an Environmental and Social Management System (“ESMS”) based on the Equator Principals. The Equator Principles, developed by the Equator Principles Association, serve as a common baseline and risk management framework for financial institutions to identify, assess, and manage environmental and social risks when financing projects such as the Elk Creek Project. NioCorp has (i) completed a comprehensive risk assessment along with management plans for high-risk areas; (ii) conducted preliminary environmental and social impact assessments; (iii) developed an ESMS, including procedures for key ESG subject areas that will assist with the management of its day-to-day activities; (iv) developed more formal community engagement procedures; (v) established a grievance mechanism for local communities and other stakeholders; (vi) completed a Climate Change Risk Assessment for the project, demonstrating the project’s resilience to climate-related risks; and (vii) completed an Environmental Justice assessment for the project, demonstrating the positive impacts that the project will have for the people of Southeast Nebraska. After a thorough review of other acquisition targets, GX believes that each business did not represent a transaction that would be as favorable to stockholders and that NioCorp is a business combination opportunity at a fair price.

What happens if I sell my GX Class A Shares before the GX Stockholder Meeting?

The record date for the GX Stockholder Meeting will be earlier than the date that the Transactions are expected to be completed. If you transfer your GX Class A Shares after the record date, but before the GX Stockholder Meeting, unless the transferee obtains from you a proxy to vote those shares, you will retain your right to vote at the GX Stockholder Meeting. However, you will not be entitled to any redemption rights with respect to such GX Class A Shares.

Who is GX’s Sponsor?

Kehler, both U.S. persons. Corbin ERISA Opportunity Fund, Ltd. and ACM Alameda Special Purpose Investment Fund II LP, both Cayman Island entities, are non-controlling members of the Sponsor that collectively own approximately 11.2% interest in the Sponsor.

The parties do not believe that any of the above facts or relationships regarding the Sponsor would, by themselves, subject a business combination to regulatory review, including review by the Committee on Foreign Investment in the United States (“CFIUS”), nor do the parties believe that if such a review were conceivable that, based solely on such facts or relationships, such business combination ultimately would be prohibited.

However, if a business combination were to become subject to regulatory review and approval requirements, including pursuant to foreign investment regulations and review by governmental entities such as CFIUS, such business combination may be delayed or ultimately prohibited. For more information, see the section entitled “Risk Factors — GX may not be able to complete an initial business combination with certain potential target companies if a proposed transaction with the target company may be subject to review or approval by regulatory authorities pursuant to certain U.S. or foreign laws or regulations.”

What vote is required to approve the proposals presented at the GX Stockholder Meeting?

The approval of the Business Combination Proposal requires the affirmative vote (in person online or by proxy) of the holders of a majority of all then outstanding shares of GX Common Stock entitled to vote thereon at the GX Stockholder Meeting.

The approval of the Charter Amendment Proposal requires the affirmative vote (in person online or by proxy) of the holders of a majority of all then outstanding shares of GX Common Stock entitled to vote thereon at the GX Stockholder Meeting, including the affirmative vote of a majority of the outstanding GX Founder Shares, voting separately as a class.

The approval of the Charter Proposal requires the affirmative vote (in person online or by proxy) of the holders of a majority of all then outstanding shares of GX Common Stock entitled to vote thereon at the GX Stockholder Meeting, including the affirmative vote of a majority of the outstanding GX Founder Shares, voting separately as a single class.

Accordingly, a GX Stockholder’s failure to vote by proxy or to vote in person online at the GX Stockholder Meeting, an abstention from voting, or a broker non-vote will have the same effect as a vote against the Business Combination Proposal, the Charter Amendment Proposal and the Charter Proposal.

The approval of Adjournment Proposal requires the affirmative vote (in person online or by proxy) of the holders of a majority of the shares of GX Common Stock entitled to vote and actually cast thereon at the GX Stockholder Meeting. Accordingly, a GX stockholder’s failure to vote by proxy or to vote in person online at the GX Stockholder Meeting, an abstention from voting, or a broker non-vote will have no effect on the outcome of any vote on these proposals.

Do NioCorp’s Shareholders need to approve the Transactions?

Yes. Holders of NioCorp Common Shares are being asked to approve, among other things, the issuance of NioCorp Common Shares to stockholders of GX in connection with the Business Combination Agreement at the NioCorp Shareholder Meeting, which will be held on March 6, 2023.

On September 25, 2022, in connection with the execution of the Business Combination Agreement, NioCorp and shareholders of NioCorp holding approximately 7.85% of NioCorp Common Shares outstanding as of the date of the Business Combination Agreement entered into the NioCorp Support Agreement, pursuant to which, among other things and subject to the terms and conditions therein, such NioCorp shareholders agreed to vote all NioCorp Common Shares beneficially owned by such shareholder in favor of the adoption and approval of the Business Combination Agreement and the Transactions, including the Share Issuance Proposal, and not to (a) transfer any of their NioCorp Common Shares (or enter into any arrangement with respect thereto) or (b) enter into any arrangement that is inconsistent with the NioCorp Support Agreement. For further information, please see the section entitled “Ancillary Agreements — NioCorp Support Agreement.”

May GX or GX’s directors, officers or advisors, or their affiliates, purchase shares in connection with the Transactions?

In connection with the stockholder vote to approve the Transactions, GX’s Sponsor, directors, officers, advisors or their affiliates may privately negotiate transactions to purchase shares prior to the Closing from stockholders who would have otherwise elected to have their shares redeemed in conjunction with a proxy solicitation pursuant to the proxy rules for a

per share pro rata portion of the Trust Account without the prior written consent of NioCorp. None of GX’s Sponsor, directors, officers or advisors, or their respective affiliates, will make any such purchases when they are in possession of any material non-public information not disclosed to the seller of such shares. Such a purchase would include a contractual acknowledgement that such stockholder, although still the record holder of such shares, is no longer the beneficial owner thereof and therefore agrees not to exercise its redemption rights. In the event that GX’s Sponsor, directors, officers or advisors, or their affiliates, purchase shares in privately negotiated transactions from the GX Public Stockholders who have already elected to exercise their redemption rights, such selling stockholders would be required to revoke their prior elections to redeem their shares. Any such privately negotiated purchases may be effected at purchase prices that are no higher than the per share pro rata portion of the Trust Account, and any such shares purchased by GX’s Sponsor, directors, officers or advisors, or their affiliates will not be voted in favor of approving the Transactions. The purpose of any such purchases of shares would be to satisfy the closing condition in the Business Combination Agreement that requires GX to have a certain amount of cash at the Closing, where it appears that such requirement would otherwise not be met.

How many votes do I have at the GX Stockholder Meeting?

GX’s stockholders are entitled to one vote at the GX Stockholder Meeting for each GX Class A Share or GX Founder Share held of record as of the record date. As of the close of business on the record date, there were 30,000,000 GX Class A Shares outstanding and 7,500,000 GX Founder Shares outstanding.

Do I have redemption rights?

If you are a holder of GX Class A Shares, you may redeem your GX Class A Shares for cash equal to your pro rata share of the aggregate amount on deposit (as of two business days prior to the Closing) in the Trust Account, which holds the proceeds of the IPO, including any amounts representing interest earned on the Trust Account, less taxes payable, and not previously released to GX to pay its taxes and for working capital purposes, upon the consummation of the Transactions; provided that you follow the specific procedures for redemption set forth in this joint proxy statement/prospectus. The per share amount GX will distribute to holders who properly redeem their shares will not be reduced by the deferred underwriting commissions GX will pay to the underwriter of its IPO if the Transactions are consummated. Holders of the outstanding GX Public Warrants do not have redemption rights with respect to such warrants in connection with the Transactions. GX’s Sponsor, officers and directors have agreed to waive their redemption rights with respect to their GX Founder Shares and any GX Class A Shares that they may have acquired during or after the IPO in connection with the completion of the Transactions. The GX Founder Shares will be excluded from the pro rata calculation used to determine the per share redemption price. For illustrative purposes, based on funds in the Trust Account as of January 13, 2023, of approximately $303,560,016, the estimated per share redemption price would have been approximately $10.11. Additionally, GX Class A Shares properly tendered for redemption will only be redeemed if the Transactions are consummated; otherwise, holders of such shares will only be entitled to a pro rata portion of the Trust Account (including interest but net of taxes payable and dissolution expenses) in connection with the liquidation of the Trust Account. If the Transactions are not consummated, GX may enter into an alternative business combination and close such transaction by March 22, 2023 (subject to the requirements of law).

Is there a limit on the number of shares I may redeem?

A GX Public Stockholder, together with any of his or her affiliates or any other person with whom he or she is acting in concert or as a “group” (as defined in Section 13(d)(3) of the Exchange Act) will be restricted from seeking redemption rights with respect to 15% or more of the GX Class A Shares. Accordingly, all shares in excess of 15% of the GX Class A Shares owned by a holder will not be redeemed. On the other hand, a GX Public Stockholder who holds less than 15% of the GX Class A Shares may redeem all of the GX Class A Shares held by him or her for cash.

Will how I vote affect my ability to exercise redemption rights?

No. You may exercise your redemption rights whether you vote your GX Class A Shares for or against the Business Combination Proposal or do not vote your shares. As a result, the Business Combination Proposal can be approved by stockholders who will redeem their GX Class A Shares and no longer remain stockholders, leaving stockholders who choose not to redeem their GX Class A Shares holding shares in a company with a less liquid trading market, fewer stockholders, less cash and the potential inability to meet the listing standards of Nasdaq.

How do I exercise my redemption rights?

In order to exercise your redemption rights, you must, (i) (A) hold GX Class A Shares, or (B) if you hold GX Class A Shares through GX Public Units, elect to separate your GX Public Units into the underlying GX Class A Shares and GX Public Warrants prior to exercising your redemption rights with respect to the GX Class A Shares and (ii) prior to 5:00 p.m. Eastern time on , 2023 (two business days before the GX Stockholder Meeting), (A) submit a written request to GX’s transfer agent that GX redeem your GX Class A Shares for cash and (B) deliver your stock to GX’s transfer agent physically or electronically through The Depository Trust Company (“DTC”). The address of Continental Stock Transfer & Trust Company (“CST”), GX’s transfer agent, is listed under the question “Who can help answer my questions?” below. GX requests that any request for redemption include the identity as to the beneficial owner making such request. Electronic delivery of your stock generally will be faster than delivery of physical stock certificates.

A physical stock certificate will not be needed if your stock is delivered to GX’s transfer agent electronically. In order to obtain a physical stock certificate, a stockholder’s broker and/or clearing broker, DTC and GX’s transfer agent will need to act to facilitate the request. It is GX’s understanding that stockholders should generally allot at least one week to obtain physical certificates from the transfer agent. However, because GX does not have any control over this process or over the brokers or DTC, it may take significantly longer than one week to obtain a physical stock certificate. If it takes longer than anticipated to obtain a physical certificate, stockholders who wish to redeem their shares may be unable to obtain physical certificates by the deadline for exercising their redemption rights and thus will be unable to redeem their shares.

Any demand for redemption, once made, may be withdrawn at any time until the deadline for exercising redemption requests and thereafter, with GX’s consent, until the vote is taken with respect to the Transactions. If you delivered your shares for redemption to GX’s transfer agent and decide within the required timeframe not to exercise your redemption rights, you may request that GX’s transfer agent return the shares (physically or electronically). You may make such request by contacting GX’s transfer agent at the phone number or address listed under the question “Who can help answer my questions?”

What are the U.S. federal income tax consequences of exercising my redemption rights?

The U.S. federal income tax consequences of any redemption of GX Class A Shares depend on particular facts and circumstances. Please see “Material U.S. Federal Income Tax Considerations—Material U.S. Federal Income Tax Considerations With Respect to the Redemption and the Transactions—Treatment of U.S. Holders With Respect to the Redemption and the Transactions—Treatment of U.S. Holders Exercising Redemption Rights With Respect to GX Class A Shares” and “Material U.S. Federal Income Tax Considerations With Respect to the Redemption and the Transactions—Treatment of Non-U.S. Holders with Respect to the Redemption and the Transactions—Treatment of Non-U.S. Holders Exercising Redemption Rights With Respect to GX Class A Shares” You should consult your tax advisor regarding the particular federal, state, local, and non-U.S. tax consequences of any redemption of GX Class A Shares that pertain to you and your situation.

If I hold GX Warrants, can I exercise redemption rights with respect to my warrants?

No. There are no redemption rights with respect to the GX Warrants.

What happens to the funds held in the Trust Account upon consummation of the Transactions?

If the Transactions are consummated, funds held in the Trust Account will be released to the Combined Company for general corporate purposes after giving effect to (i) payments made to GX Stockholders who properly exercise their redemption rights and (ii) payments for potential taxes and certain expenses incurred by NioCorp and GX in connection with the Transactions, to the extent not otherwise paid prior to the Closing.

What happens if a substantial number of the GX Public Stockholders vote in favor of the Business Combination Proposal and exercise their redemption rights?

GX Public Stockholders are not required to vote “FOR” the Business Combination Proposal in order to exercise their redemption rights. Accordingly, the Transactions may be consummated even though the funds available from the Trust Account and the number of GX Public Stockholders are reduced as a result of redemptions by GX Public Stockholders.

In no event will GX redeem GX Class A Shares in an amount that would cause NioCorp and its subsidiaries’ (including GX, as the surviving company of the Second Merger) net tangible assets to be less than $5,000,001 after giving effect to the Transactions.

Additionally, as a result of redemptions, holders of shares of the Combined Company following the Transactions may be left holding shares in a company with a less liquid trading market, fewer stockholders, less cash and the potential inability to meet the listing standards of Nasdaq.

What do I need to do now?

You are urged to carefully read and consider the information contained in this joint proxy statement/prospectus, including the financial statements, “Risk Factors” and annexes attached hereto, and to consider how the Transactions will affect you as a stockholder. You should then vote as soon as possible in accordance with the instructions provided in this joint proxy statement/prospectus on the enclosed proxy card or, if you hold your shares through a brokerage firm, bank or other nominee, on the voting instruction form provided by the broker, bank or nominee.

How do I vote?

If you were a holder of record of GX Common Stock on January 24, 2023, the record date for the GX Stockholder Meeting, you may vote with respect to the applicable proposals in person online at the GX Stockholder Meeting or by completing, signing, dating and returning the enclosed proxy card in the postage-paid envelope provided. If you choose to participate in the GX Stockholder Meeting, you can vote your shares electronically during the GX Stockholder Meeting via live webcast by visiting: https://www.cstproxy.com/gx2/2023. You will need the 12-digit meeting control number that is printed on your proxy card to enter the GX Stockholder Meeting. GX recommends that you log in at least 15 minutes before the GX Stockholder Meeting to ensure you are logged in when the GX Stockholder Meeting starts.

If on the record date your shares were held, not in your name, but rather in an account at a brokerage firm, bank, dealer or other similar organization, then you are the beneficial owner of shares held in “street name” and these proxy materials are being forwarded to you by that organization. As a beneficial owner, you have the right to direct your broker or other agent on how to vote the shares in your account. You are also invited to attend the GX Stockholder Meeting in person online. However, since you are not the stockholder of record, you may not vote your shares in person online at the GX Stockholder Meeting unless you first request and obtain a valid legal proxy from your broker or other agent. You must then e-mail a copy (a legible photograph is sufficient) of your legal proxy to CST at proxy@continentalstock.com. Beneficial owners who e-mail a valid legal proxy will be issued a 12-digit meeting control number that will allow them to register to attend and participate in the GX Stockholder Meeting. Beneficial owners who wish to attend the GX Stockholder Meeting in person online should contact CST no later than , 2023 to obtain this information.

What will happen if I abstain from voting or fail to vote at the GX Stockholder Meeting?

At the GX Stockholder Meeting, GX will count a properly executed proxy marked “ABSTAIN” with respect to a particular proposal as present for purposes of determining whether a quorum is present. For purposes of approval, an abstention or failure to vote will have the same effect as a vote against each of the Business Combination Proposal, the Charter Amendment Proposal and the Charter Proposal, and will have no effect on any of the other proposals.

What will happen if I sign and return my proxy card without indicating how I wish to vote?

Signed and dated proxies received by GX without an indication of how the stockholder intends to vote on a proposal will be voted in favor of each proposal presented to the stockholders.

How can I attend the GX Stockholder Meeting?

You may attend the GX Stockholder Meeting and vote your shares in person online during the GX Stockholder Meeting via live webcast by visiting: https://www.cstproxy.com/gx2/2023. As a registered stockholder, you received a proxy card from CST, which contains instructions on how to attend the GX Stockholder Meeting in person online, including the URL address, along with your 12-digit meeting control number. You will need the 12-digit meeting control number that is printed on your proxy card to enter the GX Stockholder Meeting. If you do not have your 12-digit meeting control number, contact CST at 917-262-2373 or e-mail CST at proxy@continentalstock.com. Please note that you will not be able to physically attend the GX Stockholder Meeting in person, but may attend the GX Stockholder Meeting in person online by following the instructions below.

You can pre-register to attend the GX Stockholder Meeting in person online starting , 2023. Enter the URL address into your browser, and enter your 12-digit meeting control number, name and email address. Once you pre-register you can vote or enter questions in the chat box. Prior to or at the start of the GX Stockholder Meeting you will need to re-log in using your 12-digit meeting control number and will also be prompted to enter your 12-digit meeting

control number if you vote in person online during the GX Stockholder Meeting. GX recommends that you log in at least 15 minutes before the GX Stockholder Meeting to ensure you are logged in when the GX Stockholder Meeting starts.

If your shares are held in “street name”, you may attend the GX Stockholder Meeting. You will need to contact CST at the number or email address above, to receive a 12-digit meeting control number and gain access to the GX Stockholder Meeting or otherwise contact your broker, bank, or other nominee as soon as possible, to do so. Please allow up to 72 hours prior to the GX Stockholder Meeting for processing your 12-digit meeting control number.

If you do not have Internet capabilities, you can listen only to the GX Stockholder Meeting by dialing 1 800-450-7155 (toll-free) if within the U.S. or Canada, or +1 857-999-9155 (standard rates apply) if outside of the U.S. and Canada, when prompted enter the pin 5151878#. This is listen only, and you will not be able to vote or enter questions during the GX Stockholder Meeting.

Do I need to attend the GX Stockholder Meeting in person online to vote my shares?

No. You are invited to attend the GX Stockholder Meeting in person online to vote on the proposals described in this joint proxy statement/prospectus. However, you do not need to attend the GX Stockholder Meeting in person online to vote your shares. Instead, you may submit your proxy by signing, dating and returning the applicable enclosed proxy card(s) in the pre-addressed postage-paid envelope. Your vote is important. GX encourages you to vote as soon as possible after carefully reading this joint proxy statement/prospectus.

If I am not going to attend the GX Stockholder Meeting in person online, should I return my proxy card instead?

Yes. After carefully reading and considering the information contained in this joint proxy statement/prospectus, please submit your proxy, as applicable, by completing, signing, dating and returning the enclosed proxy card in the postage-paid envelope provided.

If my shares are held in “street name”, will my broker, bank or nominee automatically vote my shares for me?

No. If your broker holds your shares in its name and you do not give the broker voting instructions, under the applicable stock exchange rules, your broker may not vote your shares on any of the proposals. If you do not give your broker voting instructions and the broker does not vote your shares, this is referred to as a “broker non-vote”. Broker non-votes will not be counted for purposes of determining the presence of a quorum at the GX Stockholder Meeting. Your bank, broker, or other nominee can vote your shares only if you provide instructions on how to vote. You should instruct your broker to vote your shares in accordance with directions you provide. However, in no event will a broker non-vote have the effect of exercising your redemption rights for a pro rata portion of the Trust Account, and therefore no shares as to which a broker non-vote occurs will be redeemed in connection with the Transactions.

May I change my vote after I have mailed my signed proxy card?

Yes. You may change your vote by sending a later-dated, signed proxy card to GX’s Secretary at the address listed below prior to the vote at the GX Stockholder Meeting, or attend the GX Stockholder Meeting and vote in person online. You also may revoke your proxy by sending a notice of revocation to GX’s Secretary, provided such revocation is received prior to the vote at the GX Stockholder Meeting. If your shares are held in street name by a broker or other nominee, you must contact the broker or nominee to change your vote.

What should I do if I receive more than one set of voting materials?

You may receive more than one set of voting materials, including multiple copies of this joint proxy statement/prospectus and multiple proxy cards or voting instruction cards. For example, if you hold your shares in more than one brokerage account, you will receive a separate voting instruction card for each brokerage account in which you hold shares. If you are a holder of record and your shares are registered in more than one name, you will receive more than one proxy card. Please complete, sign, date and return each proxy card and voting instruction card that you receive in order to cast your vote with respect to all of your shares.

What is the quorum requirement for the GX Stockholder Meeting?

A quorum will be present at the GX Stockholder Meeting if a majority of the GX Common Stock outstanding and entitled to vote at the GX Stockholder Meeting is represented in person online or by proxy. In the absence of a quorum, the chairman of the meeting has the power to adjourn the GX Stockholder Meeting.

As of the record date for the GX Stockholder Meeting, 18,750,001 shares of GX Common Stock would be required to achieve a quorum.

Your shares will be counted towards the quorum only if you submit a valid proxy (or your broker, bank or other nominee submits one on your behalf) or if you vote in person online at the GX Stockholder Meeting. Broker non-votes will not be counted toward the quorum requirement. If there is no quorum, the chairman of the meeting may adjourn the GX Stockholder Meeting to another date.

What happens to the GX Warrants I hold if I vote my shares of GX Common Stock against approval of the Business Combination Proposal and validly exercise my redemption rights?

Properly exercising your redemption rights as a GX stockholder does not result in either a vote “FOR” or “AGAINST” the Business Combination Proposal. If the Transactions are not completed, you will continue to hold your GX Warrants, and if GX does not otherwise consummate an initial business combination by March 22, 2023 or obtain the approval of GX stockholders to extend the deadline for GX to consummate an initial business combination, GX will be required to dissolve and liquidate, and your GX Warrants will expire worthless.

Following the Transactions, will GX securities continue to trade on a stock exchange?

No. GX anticipates that, immediately prior to the Transactions, the GX Public Units will automatically separate into the component securities and will no longer trade as a separate security. In addition, following the completion of the Transactions, the GX Class A Shares and GX Public Warrants will be delisted from Nasdaq and deregistered under the Exchange Act. For more information, see the question above entitled “What will GX stockholders receive if the Transactions are completed?”

How does the Sponsor intend to vote on the proposals?

GX’s Sponsor, directors and officers have, for no additional consideration, agreed to vote any shares of GX Common Stock owned by them in favor of the Transactions, including their GX Founder Shares and any GX Class A Shares purchased after the IPO (including in open market and privately negotiated transactions). As of the record date, GX’s Sponsor, officers and directors beneficially own an aggregate of approximately 20% of the outstanding shares of GX Common Stock.

Who will solicit and pay the cost of soliciting proxies?

GX will pay the cost of soliciting proxies for the GX Stockholder Meeting. GX has engaged Morrow Sodali LLC (“Morrow”) to assist in the solicitation of proxies for the GX Stockholder Meeting. GX has agreed to pay Morrow a fee of up to $32,500, plus Morrow’s out-of-pocket expenses. GX will reimburse Morrow for reasonable out-of-pocket expenses and will indemnify Morrow and its affiliates against certain claims, liabilities, losses, damages and expenses. GX will also reimburse banks, brokers and other custodians, nominees and fiduciaries representing beneficial owners of shares of the GX Class A Shares for their expenses in forwarding soliciting materials to beneficial owners of GX Class A Shares and in obtaining voting instructions from those owners. GX’s directors, officers and employees may also solicit proxies by telephone, by facsimile, by mail, on the Internet or in person. They will not be paid any additional amounts for soliciting proxies.

Who can help answer my questions?

If you have questions about the proposals to be voted on at the GX Stockholder Meeting, or if you need additional copies of this joint proxy statement/prospectus, the proxy card or the consent card you should contact GX’s proxy solicitor at:

Morrow Sodali LLC
333 Ludlow Street, 5th Floor, South Tower
Stamford, Connecticut 06902
Tel: (800) 662-5200 (toll-free) or
(203) 658-9400 (banks and brokers can call collect)
Email: GXII.info@investor.morrowsodali.com

You may also contact GX at:

Michael G. Maselli, President
GX Acquisition Corp. II

1325 Avenue of the Americas, 28^th Floor
New York, NY 10019
Tel: (212) 616-3700
Email: michael.maselli@trimarancapital.com

To obtain timely delivery, GX Securityholders must request the materials no later than five business days prior to the GX Stockholder Meeting.

You may also obtain additional information about GX from documents filed with the SEC by following the instructions in the section entitled “Where You Can Find Additional Information”.

If you intend to seek redemption of your GX Class A Shares, you will need to send a letter demanding redemption and deliver your stock (either physically or electronically) to GX’s transfer agent prior to 5:00 p.m., New York time, on the second business day prior to the GX Stockholder Meeting. If you have questions regarding the certification of your position or delivery of your stock, please contact:

Continental Stock Transfer & Trust Company
One State Street Plaza, 30^th Floor
New York, New York 10004
Attention: Mark Zimkind
E-mail: mzimkind@continentalstock.com

SUMMARY

This summary highlights information contained elsewhere in this joint proxy statement/prospectus. NioCorp and GX urge you to read carefully the remainder of this joint proxy statement/prospectus, including the attached annexes, the documents incorporated by reference into this joint proxy statement/prospectus and the other documents to which NioCorp and GX have referred you because this section does not provide all of the information that might be important to you with respect to the Transactions and the related matters being considered and voted on by the GX Stockholders at the GX Stockholder Meeting and by the NioCorp Shareholders at the NioCorp Shareholder Meeting. See also the section entitled “Where You Can Find Additional Information” on page [●]. NioCorp and GX have included page references to direct you to a more complete description of the topics presented in this summary.

Parties to the Transactions

NioCorp Developments Ltd.

7000 South Yosemite Street

Suite 115

Centennial, Colorado 80112

(720) 639-4647

NioCorp is organized under the laws of the province of British Columbia, Canada. NioCorp is a mineral exploration company engaged in the acquisition, exploration, and development of mineral properties. NioCorp, through ECRC, is developing a superalloy materials project that, if and when developed, will produce niobium, scandium, and titanium products. Known as the “Elk Creek Project,” it is located near Elk Creek, Nebraska, in the southeast portion of the state. NioCorp’s primary business strategy is to advance its Elk Creek Project to commercial production. NioCorp is focused on obtaining additional funds to carry out its near-term planned work programs associated with securing the project financing necessary to complete mine development and construction of the Elk Creek Project.

NioCorp Common Shares trade on the TSX under the symbol “NB,” on the U.S. Over-the-Counter Bulletin Board and the OTCQX under the symbol “NIOBF” and on the Frankfurt Stock Exchange as “BR3.” For additional information about NioCorp and the Elk Creek Project, see the section entitled “Information About NioCorp” beginning on page [●] of this joint proxy statement/prospectus.

Big Red Merger Sub Ltd

7000 South Yosemite Street

Suite 115

Centennial, Colorado 80112

(720) 639-4647

Merger Sub is a Delaware corporation and a direct wholly owned subsidiary of NioCorp. Merger Sub is newly formed and was organized for the purpose of consummating the Transactions. Merger Sub has engaged in no business activities to date and it has no material assets or liabilities of any kind, other than those incident to its formation and those incurred in connection with the Transactions.

GX Acquisition Corp. II

1325 Avenue of the Americas
28th Floor
New York, NY 10019
(212) 616-3700

GX is a blank check company incorporated in Delaware on September 24, 2020 for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination involving GX and one or more businesses. Upon the Closing, GX will be a subsidiary of NioCorp.

GX Public Units, GX Class A Shares and GX Public Warrants are currently listed on the Nasdaq, under the symbols “GXIIU”, “GXII” and “GXIIW”, respectively. Following the Closing, the GX Public Units, GX Class A Shares and GX Public Warrants will be delisted from the Nasdaq and deregistered under the Exchange Act.

For additional information about GX, see the section entitled “Information About GX” beginning on page [●] of this joint proxy statement/prospectus.

The Business Combination Agreement and the Transactions

On September 25, 2022, NioCorp, GX and Merger Sub entered into the Business Combination Agreement, a copy of which is attached as Annex A hereto. Pursuant to the Business Combination Agreement, among other transactions, the following transactions will occur: (i) Merger Sub will merge with and into GX, with GX surviving the merger, referred to as the First Merger; (ii) all GX Class A Shares that are held by GX Public Stockholders who have not elected to exercise their redemption rights in connection with the Transactions shall be converted into First Merger Class A Shares in GX, as the surviving company in the First Merger; (iii) NioCorp will purchase all First Merger Class A Shares held by the GX Public Stockholders in exchange for NioCorp Common Shares, referred to as the Exchange; (iv) NioCorp will assume the GX Warrant Agreement and each GX Warrant that was issued and outstanding immediately prior to the effective time of the Exchange will be converted into a NioCorp Assumed Warrant; (v) all of the First Merger Class A Shares will be contributed by NioCorp to Intermediate Holdco in exchange for additional shares of Intermediate Holdco, resulting in GX becoming a direct subsidiary of Intermediate Holdco; (vi) ECRC will merge with and into GX, with GX surviving the merger as a direct subsidiary of Intermediate Holdco, referred to as the Second Merger; and (vii) following the effective time of the Second Merger, each of NioCorp and GX, as the surviving company of the Second Merger, will effectuate a reverse stock split with the ratio to be mutually agreed by the parties. In addition, pursuant to the Business Combination Agreement, the parties will enter into the Exchange Agreement, under which holders of 48,645,707 Second Merger Class B Shares (the “Vested Shares”) are entitled to exchange any or all of the Vested Shares for NioCorp Common Shares on a one-for-one basis, subject to certain equitable adjustments, in accordance with the terms of the Exchange Agreement, which are further described in Note 4 of the Notes to the Unaudited Pro Forma Condensed Combined Financial Information included elsewhere in this joint proxy statement/prospectus. As a result of the Transactions, GX will become a subsidiary of NioCorp.

For more information about the Business Combination Agreement, see the section of this joint proxy statement/prospectus entitled “The Business Combination Agreement.”

Consideration (page [●])

Pursuant to the Business Combination Agreement, upon consummation of the First Merger, each GX Class A Share that is held by a GX Public Stockholder shall be converted into a First Merger Class A Share. In connection with the Exchange, NioCorp will exercise its unilateral option to purchase each First Merger Class A Share held by the GX Public Stockholders in exchange for 11.1829212 NioCorp Common Shares. As a result, each GX Public Stockholder who does not elect to exercise their redemption rights in connection with the Transactions will ultimately be issued NioCorp Common Shares.

Upon consummation of the First Merger, each Class B share in GX (other than certain shares that may be forfeited in accordance with the GX Support Agreement) will be converted into one First Merger Class B Share of GX, as the surviving company in the First Merger. Upon consummation of the Second Merger, each First Merger Class B Share shall be converted into 11.1829212 Second Merger Class B Shares of GX, as the surviving company in the Second Merger. Each Second Merger Class B Share will be exchangeable into NioCorp Common Shares on a one-for-one basis, subject to certain equitable adjustments, in accordance with the terms of the Exchange Agreement as further discussed in Note 4 of the Notes to the Unaudited Pro Forma Condensed Combined Financial Information.

In connection with the First Merger and the assumption by NioCorp of the GX Warrant Agreement, each GX Warrant that is issued and outstanding immediately prior to the Exchange Time shall be converted into one NioCorp Assumed Warrant pursuant to the GX Warrant Agreement. Each NioCorp Assumed Warrant shall be exercisable solely for NioCorp Common Shares, and the number of NioCorp Common Shares subject to each NioCorp Assumed Warrant shall be equal to the number of shares of GX common stock subject to the applicable GX Warrant multiplied by 11.1829212.

Following the effective time of the Second Merger, NioCorp will effectuate a reverse stock split of the issued NioCorp Common Shares, and GX will effectuate a proportionate reverse stock split of the Second Merger Class A Shares and the Second Merger Class B Shares at a to-be-determined ratio.

Conditions to the Transactions (page [●])

NioCorp Common Shares to be issued in connection with the Transactions, (iv) receipt of approval for listing on Nasdaq of the NioCorp Assumed Warrants, (v) receipt of approval from the TSX with respect to the issuance and listing of the NioCorp Common Shares issuable in connection with the Transactions, (vi) that NioCorp and its subsidiaries (including GX, as the surviving company of the Second Merger will have at least $5,000,001 of net tangible assets upon the consummation of the Transactions, after giving effect to any redemptions by GX Public Stockholders and after payment of underwriters’ fees or commissions, (vii) that, at Closing, NioCorp and its subsidiaries (including GX, as the surviving company of the Second Merger) will have received cash in an amount equal to or greater than $15,000,000, subject to certain adjustments (which amount may be satisfied with funds in the Trust Account or otherwise, as further described under “The Transactions—NioCorp’s Reasons for the Transactions and Recommendation of the NioCorp Board”), and (viii) the absence of any injunctions enjoining or prohibiting the consummation of the Business Combination Agreement. Each of the foregoing conditions, in addition to the other customary conditions contained in the Business Combination Agreement, may be waived by the party or parties in whose favor such closing condition is made (to the extent permitted by applicable law), except that the first, second and eighth conditions listed above may not be waived pursuant to applicable law and the third and fourth conditions may not be waived without recirculation and resolicitation.

Representations, Warranties and Covenants (page [●])

The Business Combination Agreement contains customary representations, warranties and covenants of (i) NioCorp and Merger Sub and (ii) GX, relating to, among other things, their respective abilities and authority to enter into the Business Combination Agreement and their respective capitalization.

Closing and Effective Time of the Transactions (page [●])

The Closing of the Transactions will be no later than the second business day following the satisfaction or waiver of all of the closing conditions as set forth in the Business Combination Agreement(the “Closing Date”). At the Closing, the parties to the Business Combination Agreement will cause each of the First Merger and the Second Merger to be consummated, in each case by filing a certificate of merger with the Secretary of State of Delaware and, with respect to the Second Merger only, filing articles of merger with the Secretary of State of Nebraska. As set forth above, immediately following the effective time of the Second Merger each of NioCorp and GX, as the surviving company of the Second Merger, will effectuate the applicable reverse stock split.

As of the date of this joint proxy statement/prospectus, the parties expect that the Closing will occur during the first calendar quarter of 2023. However, there can be no assurance as to when or if the Closing will occur.

Termination; Termination Fee (page [●])

The Business Combination Agreement may be terminated by NioCorp or GX under certain circumstances. Upon termination of the Business Combination Agreement in specified circumstances, NioCorp must pay GX a termination fee of $15,000,000 (the “Base Termination Fee”). Such specified circumstances include, among others, termination of the Business Combination Agreement by NioCorp in order to enter into an agreement providing for a Superior Proposal, termination by GX for a change of recommendation of the NioCorp Board, or a material breach of certain of NioCorp’s covenants relating to soliciting acquisition proposals.

In addition, upon termination of the Business Combination Agreement in other specified circumstances, NioCorp is required to pay a termination fee in the amount of $25,000,000 (the “Intentional Breach Termination Fee”). Such specified circumstances include, among others, termination by GX as a result of a willful and material breach by NioCorp such that certain conditions to Closing would not be satisfied at Closing (subject to a cure period), or as a result of NioCorp’s failure to consummate the Closing of the Transactions within five business days after GX has irrevocably confirmed in writing that it is prepared to consummate the Closing and all the conditions to Closing have been satisfied.

In addition, upon termination of the Business Combination Agreement in a situation in which GX will be entitled to the Base Termination Fee or the Intentional Breach Termination Fee, NioCorp is also required to pay an amount equal to the sum of all documented and reasonable out-of-pocket expenses paid or payable by GX and the Sponsor in connection with the Business Combination Agreement and the Transactions, not to exceed $5,000,000.

Pursuant to the Business Combination Agreement, in no event will GX be entitled to both the Base Termination Fee and the Intentional Breach Termination Fee.

GX’s Reasons for the Transactions and Recommendation of the GX Board (page [●])

After careful consideration, the GX Board recommends that its stockholders vote “FOR” the approval of the business combination and the Transactions contemplated thereby. The factors considered by the GX Board include, but were not limited to, the following:

●

Important Product. Upon completion of the Elk Creek Project, NioCorp is expected to produce Niobium, Scandium and Titanium, which are among the most critical minerals to U.S. national security. The June 2022 Feasibility Study shows attractive potential economic returns of $2.8 billion net present value for these minerals, and forecasted demand by 2026 is expected to greatly exceed current supply, driven by the focus on development of lighter-weight, more fuel efficient aircraft and vehicles, as well as construction of stronger, lighter steels for buildings and other infrastructure projects;

●

Feasibility Study. NioCorp has a published feasibility study compliant with S-K 1300 and filed with the SEC that provided meaningful details regarding the Elk Creek Project, which was reviewed by certain qualified professionals;

●

Rare Earth Elements. NioCorp is in the process of evaluating the potential to add certain rare earth elements to its mine production plan, that if successful, could increase the projects revenue and potential value;

●

Growth Prospects. NioCorp intends to produce critical minerals that are increasing in demand globally, driven by the transition to net zero emissions using methods such as electrification, light weighting and more durable materials;

●

Experienced and Proven Management Team. NioCorp has a strong management team with decades of combined experience in mineral production, and the senior management team of NioCorp intends to remain with NioCorp in the capacity of officers and/or directors, which will provide helpful continuity in advancing NioCorp’s strategic and growth goals;

●

ESG Mission. NioCorp’s mission is to accelerate the global transition to a lower carbon economy by serving as a reliable U.S. supplier of sustainably produced critical minerals, which highlights NioCorp’s focus on ESG values, and is further demonstrated by the Elk Creek Project’s alignment with the Equator Principles ESG Framework;

●

Supply Chain Security. The United States is currently dependent on foreign suppliers for most of NioCorp’s critical minerals, and as the Elk Creek Project (located near Elk Creek, Nebraska) is anticipated to be able to supply some of the world’s largest industries and sustainable technologies with made-in-USA critical minerals, NioCorp is expected to offer a production solution in a low-risk jurisdiction compared to other politically sensitive and unreliable supply locations outside of the United States; and

●

Competitive Advantage. NioCorp has several valuable competitive advantages with its expected mining operations at the Elk Creek Project, including its location on private land with extensive nearby infrastructure, strong community support as well as state and local government support, obtaining key federal and state permits required to proceed to the start of construction, its position to become the second largest indicated rare earth resource in the United States with intended production of high-value critical minerals and its focus on sustainability.

For a further description of the GX Board’s reasons for the approval of the business combination and the Transactions contemplated thereby, see the section of this joint proxy statement/prospectus entitled “The Transactions — GX’s Reasons for the Transactions and Recommendation of the GX Board.”

NioCorp’s Reasons for the Transactions and Recommendation of the NioCorp Board (page [●])

After careful consideration, the NioCorp Board recommends that the NioCorp Shareholders vote in favor of all matters related to the Transactions. The factors considered by the GX Board include, but were not limited to, the following:

●

Valuation. The approximately $0.89 per NioCorp Common Share equity rollover value represents a premium of approximately 14% to the NioCorp Common Share spot price and of approximately 12.6% to the NioCorp Common Share 20-day volume-weighted average price, as of September 23, 2022;

●

Anticipated Acceleration of Financing Efforts. The Transactions have the potential to (1) provide NioCorp with up to $285 million in net cash proceeds at the consummation of the Transactions, depending upon the amount of redemptions by GX Public Stockholders, and up to an additional $80 million over the next three years, depending on the consummation of other additional financing arrangements that NioCorp and GX intend to pursue prior to and following the expected Closing of the Transactions and (2) significantly accelerate NioCorp’s efforts to obtain the required Elk Creek Project financing by increasing exposure to institutional investors looking to make strategic investments in critical minerals plays that are crucial to the world’s clean energy transition;

●

Definitive Yorkville Financing Agreements. The signing of definitive agreements on January 26, 2023 for two separate financing packages with Yorkville, where such financings could provide NioCorp with access to up to an additional $80 million to help advance the Elk Creek Project. The financings contemplated by the Yorkville Financing Agreements include $16 million in convertible debentures that are expected to be funded at the closing of the Transactions and a standby equity purchase facility pursuant to which NioCorp will have the ability to require Yorkville, subject to the conditions set out in the Yorkville Equity Facility Financing Agreement, to purchase up to $65 million of NioCorp Common Shares;

●

Anticipated Benefits of Nasdaq Listing. A listing on Nasdaq, which is an established national exchange in the United States, would provide broader access to capital and financing alternatives and would otherwise enhance NioCorp’s public profile;

●

Minimum Cash Condition. The consummation of the Transactions is subject to the satisfaction or waiver of certain closing conditions contained in the Business Combination Agreement, including, among other things, that, at the Closing, NioCorp and its subsidiaries (including GX, as the surviving company of the Second Merger) will have cash at Closing in an amount equal to or greater than the Closing Cash Minimum (with Closing cash calculated as follows: (1) cash to be released from the Trust Account (after giving effect to redemptions but prior to the payment of any transaction expenses), plus (2) cash advanced under any financing arrangement contemplated by the Business Combination Agreement, plus (3) cash raised at or following the signing of the Business Combination Agreement, and paid to GX or NioCorp prior to or at the Closing, including pursuant to any financing contemplated by the Business Combination Agreement or any other debt or equity or equity-linked financing or investment, less (4) Company Operating Cash (as defined in the Business Combination Agreement), if any, to the extent available to NioCorp as of the Closing (provided that any amounts raised in excess of the Company Operating Cash Cap Cash (as defined in the Business Combination Agreement) will be included in the calculation of cash at Closing), less (5) the lesser of (a) $2,000,000 and (b) the excess, if any, of (i) GX, Merger Sub and NioCorp’s reasonable estimate of GX's tax liability under Section 4501 of the Code that will be incurred as a result of the Transactions (calculated in accordance with the terms of the Business Combination Agreement) (the “Excise Tax Amount”) over (ii) $1,000,000, and less (6) in the event that a tax advisor is retained in connection with the calculation of the Excise Tax Amount, 50% of such tax advisor's fee), which is estimated to require that, in order to satisfy such Closing Cash Condition, no more than 28,290,000 GX Class A Shares, or 94.3% of GX Class A Shares outstanding, are redeemed by GX Public Stockholders from the Trust Account, assuming that the Yorkville Financings or other financing is not obtained and subject to adjustment for any Company Operating Cash, Excise Tax Amount and related tax advisor’s fee, as applicable;

●

Alignment of Interests with Sponsor. (1) The Sponsor and certain of GX’s directors and officers have waived any redemption rights in connection with the Transactions with respect to any GX Founder Shares and any GX Class A Shares and (2) 3,150,000 GX Founder Shares are subject to post-Closing vesting conditions, to vest in two equal tranches only if the VWAP of NioCorp Common Shares has equaled or exceeded $13.42 divided by the Exchange Ratio, and $16.77 divided by the Exchange Ratio, respectively (as adjusted for stock splits (including the Reverse Stock Split), recapitalizations and similar events) for 20 trading days within any 30 trading-day period;

●

Fairness Opinion. GenCap’s opinion rendered to the NioCorp Board on September 25, 2022, which was subsequently confirmed by delivery of a written opinion dated as of September 25, 2022, that, as of the date of its opinion and based upon and subject to the factors, assumptions, considerations, limitations and other matters set forth in GenCap’s written opinion, that the Transactions (including the Exchange Ratio) are fair, from a financial point of view, to the NioCorp shareholders, as more fully described under “The Transactions — Opinion of NioCorp’s Financial Advisor” and in the full text of the written opinion of GenCap, which is attached as Annex E to this joint proxy statement/prospectus;

●

Employment Agreements. The continuity of NioCorp management upon the consummation of the Transactions due to the execution of the Key Employee Agreements;

●

Terms of the Business Combination Agreement. The NioCorp Board’s and its advisors’ review of the financial and other terms of the Business Combination Agreement, including the parties’ representations, warranties and covenants, the conditions to their respective obligations to complete the Transactions, the termination provisions, the likelihood of the completion of the Transactions and the likely time period necessary to complete the Transactions.

For a further description of the NioCorp Board’s reasons for the approval of the Transactions, see the section of this joint proxy statement/prospectus entitled “The Transactions — NioCorp’s Reasons for the Transactions and Recommendation of the NioCorp Board.”

Opinion of GX’s Financial Advisor (page [●])

GX retained Scalar to act as its financial advisor in connection with the Transactions. Scalar rendered its opinion to the GX Board that, as of September 25, 2022 and based upon and subject to the factors and assumptions set forth therein, the consideration to be received by the holders of GX Class A Shares pursuant to the Business Combination Agreement is fair, from a financial point of view, to such stockholders. For a description of Scalar’s fairness opinion, see the section of this joint proxy statement/prospectus entitled “The Transactions — Opinion of GX’s Financial Advisor.”

Opinion of NioCorp’s Financial Advisor (page [●])

NioCorp retained GenCap to act as its financial advisor in connection with the Transactions. On September 25, 2022, GenCap rendered its oral opinion to the NioCorp Board (which was subsequently confirmed in writing by delivery of a written opinion dated September 25, 2022) to the effect that, subject to the assumptions, qualifications, limitations and other matters considered by GenCap in connection with the preparation of its opinion, as of such date, the Transactions are fair, from a financial point of view, to the NioCorp Shareholders. For a description of GenCap’s fairness opinion, see the section of this joint proxy statement/prospectus entitled “The Transactions — Opinion of NioCorp’s Financial Advisor.”

Accounting Treatment of the Transactions (page [●])

The business combination will be accounted for as a recapitalization in accordance with GAAP. Under this method of accounting, GX will be treated as the “acquired” company for financial reporting purposes. Accordingly, the Transactions are treated as the equivalent of NioCorp issuing NioCorp Common Shares for the net assets of GX, accompanied by a recapitalization. The net assets of GX will be stated at historical cost, with no goodwill or other intangible assets recorded. Operations prior to the business combination will be those of NioCorp.

Treatment of NioCorp Group Equity Awards (page [●])

All NioCorp options outstanding at the Closing shall remain outstanding immediately following the Closing, at which time the NioCorp Board will determine whether an equitable adjustment to the NioCorp Options should be made in connection with the Reverse Stock Split, consistent with the NioCorp Developments Ltd. Long Term Incentive Plan, effective as of November 9, 2017 (the “NioCorp Incentive Plan”) and in consultation with GX.

Organizational Structure

The following diagram illustrates, in a simplified form, the organizational structure of NioCorp and GX as of the date of this joint proxy statement/prospectus and prior to the consummation of the Transactions.

The following diagram illustrates, in a simplified form, the organizational structure of the Combined Company immediately following consummation of the Transactions. NioCorp Shareholders and GX Stockholders are expected to own the percentages of outstanding NioCorp Common Shares as set forth in “GX Proposal No. 1 — The Business Combination Proposal — Ownership of the Combined Company After the Closing.”

Ownership of the Combined Company After the Closing (page [●])

Assuming that all of the Second Merger Class B Shares are exchanged into NioCorp Common Shares, immediately following completion of the Transactions, it is expected that the current NioCorp Shareholders and the current GX Stockholders will own the following percentages, respectively, of the outstanding NioCorp Common Shares under the following redemption scenarios (not including the potential dilutive impact of the Yorkville Financings - please see the section entitled “Yorkville Financings”):

	No Redemptions		50% Redemption		Maximum Redemption
Shareholder	Shares	Ownership and Voting Interest	Shares	Ownership and Voting Interest	Shares	Ownership and Voting Interest
GX Class A Holders	335,487,636	50.3%	167,743,818	33.6%	2,348,413	0.7%
GX Class B Holders⁽¹⁾	47,650,427	7.1%	47,650,427	9.5%	47,650,427	14.3%
Others⁽²⁾	4,769,574	0.7%	4,769,574	1.0%	4,769,574	1.4%
NioCorp Shareholders	279,393,227	41.9%	279,393,227	55.9%	279,393,227	83.6%
Total Shares Outstanding	667,300,864	100.0%	499,557,046	100.0%	334,161,641	100.0%

	(1)	Excludes 34,230,920 Earnout Shares that are unvested and held by the GX Class B stockholders

	(2)	Includes 3,343,693 Common Shares issued to Cantor Fitzgerald, 788,455 Common Shares issued under the Equity Facility, and 637,426 Common Shares issued to BTIG.

Assuming that none of the Second Merger Class B Shares are exchanged into NioCorp Common Shares, immediately following completion of the Transactions, it is expected that the current NioCorp Shareholders and the current GX Stockholders will own the following percentages, respectively, of the outstanding NioCorp Common Shares under the following redemption scenarios (not including the potential dilutive impact of the Yorkville Financings - please see the section entitled “Yorkville Financings”):

	No Redemptions		50% Redemption		Maximum Redemption
Shareholder	Shares	Ownership and Voting Interest	Shares	Ownership and Voting Interest	Shares	Ownership and Voting Interest
GX Class A Holders	335,487,636	54.1%	167,743,818	37.1%	2,348,413	0.8%
GX Class B Holders	—	—	—	—	—	—
Others⁽¹⁾	4,769,574	0.8%	4,769,574	1.1%	4,769,574	1.7%
NioCorp Shareholders	279,393,227	45.1%	279,393,227	61.8%	279,393,227	97.5%
Total Shares Outstanding	619,650,437	100.0%	451,906,619	100.0%	286,511,214	100.0%

	(1)	Includes 3,343,693 Common Shares issued to Cantor Fitzgerald, 788,455 Common Shares issued under the Equity Facility, and 637,426 Common Shares issued to BTIG.

The following table illustrates the potential impact of redemptions on the per share value of the shares owned by non-redeeming shareholders as well as the effective underwriting fees at the following redemption levels:

	Redemption Level
	99.3%	75%	50%	25%	0%
Implied Value Per NioCorp Share	$0.7805	$0.8031	$0.8185	$0.8295	$0.8377
Implied Value Per Share - Impact of Underwriter Fees	$0.7653	$0.7909	$0.8084	$0.8209	$0.8301
Effective Underwriting Fee %	1.94%	1.52%	1.23%	1.04%	0.90%

Implied Value Per GX Share	$8.7286	$8.9808	$9.1536	$9.2763	$9.3679
Implied Value Per Share - Impact of Underwriter Fees	$8.5588	$8.8448	$9.0406	$9.1796	$9.2835
Effective Underwriting Fee %	1.94%	1.52%	1.23%	1.04%	0.90%

Further, assuming the no redemption scenario, the Sponsor would own 7.1% or 11.7% of the Combined Company, and assuming the maximum redemption scenario, the Sponsor would own 14.3% or 22.2% of the Combined Company, excluding the Earnout Shares or including the Earnout Shares respectively. The value of such shares on an as-converted basis proforma for the Transactions and based on the trading price of NioCorp stock of $0.82 per share is $39.1 million excluding the Earnout Shares and $67.1 million including the Earnout Shares. This compares to a price paid of $25,000 for the GX Founder Shares and $8,500,000 for the GX Founder Warrants.

However, on a fully diluted basis, including the shares issued to Cantor and BTIG in connection with their fee arrangements as part of the Transactions and assuming treating all dilutive securities on an as-converted basis, including the GX Warrants, the outstanding options, warrants and convertible notes of NioCorp and the anticipated NioCorp Convertible Debentures and NioCorp Financing Warrants, assuming the no redemption scenario, the Sponsor would own 12.2% or 15.3% of the Combined Company, and assuming the maximum redemption scenario, the Sponsor would own 19.1% or 23.7% of the Combined Company, excluding the Earnout Shares or including the Earnout Shares respectively. The value of such shares on an as-converted basis proforma for the Transactions and based on the trading price of NioCorp stock of $0.82 per share is $39.1 million excluding the Earnout Shares and $67.1 million including the Earnout Shares. This compares to a price paid of $25,000 for the GX Founder Shares. In addition, based on a price of $0.78 per warrant, the value of the GX Founder Warrants, is $4.4 million. This compares to a price paid of $25,000 for the GX Founder Shares and $8.5 million for the GX Founder Warrants.

	No Redemptions of Public Shares			Maximum Redemptions of Public Shares
	Number of NioCorp Common Shares	Percentage of total number of NioCorp Common Shares		Number of NioCorp Common Shares	Percentage of total number of NioCorp Common Shares
*(1) No Dilution – Without Earnout:*
NioCorp Common Shares held by the Sponsor	47,650,427	7.1	%⁽¹⁾	47,650,427	14.3	%⁽²⁾

*(2) No Dilution – With Earnout:*
NioCorp Common Shares held by the Sponsor	81,881,347	11.7	%⁽³⁾	81,881,347	22.2	%⁽⁴⁾

*(3) Fully Diluted – Without Earnout:*
NioCorp Common Shares held by the Sponsor	47,650,427	5.2	%⁽⁵⁾	47,650,427	8.2	%⁽⁶⁾
NioCorp Common Shares underlying NioCorp Assumed Warrants held by the Sponsor	63,369,890	6.9	%⁽⁵⁾	63,369,890	10.9	%⁽⁶⁾
Total	111,020,317	12.2	%⁽⁵⁾	111,020,317	19.1	%⁽⁶⁾

*(4) Fully Diluted – With Earnout:*
NioCorp Common Shares held by the Sponsor	81,881,347	8.6	%⁽⁷⁾	81,881,347	13.3	%⁽⁸⁾
NioCorp Common Shares underlying NioCorp Assumed Warrants held by the Sponsor	63,369,890	6.7	%⁽⁷⁾	63,369,890	10.3	%⁽⁸⁾
Total	145,251,237	15.3	%⁽⁷⁾	145,251,237	23.7	%⁽⁸⁾

(1)

Percentages calculated over a total of 667,300,864 NioCorp Common Shares. Figures have been rounded for ease of presentation.

(2)

(3)

Percentages calculated over a total of 701,531,784 NioCorp Common Shares. Figures have been rounded for ease of presentation.

(4)

(5)

(6)

(7)

(8)

Listing (page [●])

The completion of the Transactions is conditioned upon the approval for listing of the NioCorp Common Shares issuable pursuant to the Transactions on the TSX and Nasdaq, and listing of the NioCorp Assumed Warrants on Nasdaq, in each case at or prior to the effective time, subject to official notice of issuance. Although this condition may be waived without further solicitation of the NioCorp Shareholders or GX Stockholders or recirculation of this joint proxy statement/prospectus, NioCorp has applied for listing of the NioCorp Common Shares and NioCorp Assumed Warrants on Nasdaq and is in the process of seeking such approval for listing. NioCorp currently expects to qualify for listing on the Nasdaq Capital Market (after giving effect to the reverse stock split), but intends to pursue listing on either the Nasdaq Global Market or Nasdaq Global Select Market if the Combined Company meets the requisite listing standards. NioCorp also intends to apply for listing of the NioCorp Common Shares to be issued in connection with the Transactions and the Yorkville Financings with the TSX. Neither Nasdaq nor TSX has conditionally approved any NioCorp listing application and there is no assurance that such exchanges will approve any listing application.

Following the Closing, the GX Public Units, GX Class A Shares and GX Public Warrants will be delisted from Nasdaq and deregistered under the Exchange Act.

Ancillary Agreements

NioCorp Support Agreement (page [●])

On September 25, 2022, concurrently with the execution of the Business Combination Agreement, GX, NioCorp and the directors and officers of NioCorp entered into the NioCorp Support Agreement, a copy of which is attached to this joint proxy statement/prospectus as Annex I, pursuant to which the parties agreed, among other things, to vote in favor of the NioCorp Proposals.

For more information about the NioCorp Support Agreement, see the section of this joint proxy statement/prospectus entitled “Ancillary Agreements — NioCorp Support Agreement.”

GX Support Agreement (page [●])

On September 25, 2022, concurrently with the execution of the Business Combination Agreement, NioCorp, GX, the Sponsor and certain officers and directors of GX executed the GX Support Agreement, a copy of which is attached to this joint proxy statement/prospectus as Annex J, pursuant to which, among other things, the Sponsor and certain officers and directors of GX have agreed among other things to vote their shares of GX Common Stock in favor of (a) an amendment to the GX Existing Charter to eliminate the automatic conversion of GX Founder Shares at the time of a Business Combination (as defined in the GX Existing Charter), (b) the Transactions, and (c) any other proposals that are necessary to effectuate the Transactions. With respect to certain Second Merger Class B Shares that are subject to an earnout period, the Sponsor and certain officers and directors of GX also agreed not to transfer such shares until NioCorp Common Shares achieve a trading price exceeding certain dollar thresholds set forth in the GX Support Agreement, subject to the terms and conditions contemplated by the GX Support Agreement. Such shares will be forfeited if the NioCorp Common Shares do not achieve the specified trading prices prior to the tenth anniversary of the Closing Date.

For more information about the GX Support Agreement, see the section of this joint proxy statement/prospectus entitled “Ancillary Agreements — GX Support Agreement.”

Exchange Agreement (page [●])

Pursuant to the Business Combination Agreement, in connection with the Closing, NioCorp, GX and the Sponsor will enter into the Exchange Agreement, a copy of the form of which is attached to this joint proxy statement/prospectus as Annex H, pursuant to which, among other things, the Sponsor will be entitled to exchange any or all of its shares of Second Merger Class B Shares in GX (subject, in the case of Second Merger Class B Shares subject to an earnout period, to achievement of the applicable trading prices) for NioCorp Common Shares on a one-for-one basis, subject to certain equitable adjustments, in accordance with the terms of the Exchange Agreement. Under certain circumstances, and subject to certain exceptions, NioCorp may instead settle all or a portion of any exchange pursuant to the terms of the Exchange Agreement in cash, in lieu of NioCorp Common Shares, based on a volume-weighted average price of NioCorp Common Shares.

For more information about the Exchange Agreement, see the section of this joint proxy statement/prospectus entitled “Ancillary Agreements — Exchange Agreement.”

Registration Rights and Lock-Up Agreement (page [●])

Pursuant to the Business Combination Agreement, in connection with the Closing, NioCorp, GX, the Sponsor, in its capacity as a shareholder of GX, the pre-Closing directors and officers of NioCorp and the other parties thereto will enter into the Registration Rights and Lock-Up Agreement, a copy of the form of which is attached to this joint proxy statement/prospectus as Annex G, pursuant to which, among other things, NioCorp will be obligated to file a shelf registration statement to register the resale of certain securities of NioCorp held by the parties after the Closing. The Registration Rights and Lock-Up Agreement will also provide for certain “lock-up” restrictions with respect to the certain NioCorp securities held after the Closing by the Sponsor and the pre-Closing directors and officers of NioCorp.

For more information about the Registration Rights and Lock-Up Agreement, see the section of this joint proxy statement/prospectus entitled “Ancillary Agreements—Registration Rights and Lock-Up Agreement.”

Key Employee Agreements (page [●])

On September 25, 2022, in connection with entry into the Business Combination Agreement, certain executive officers of NioCorp entered into Employment Agreements with ECRC. Subject to each such officer entering into a Restrictive Covenant Agreement (as defined herein) with ECRC prior to the Closing, the Employment Agreements will become effective

upon the Closing, and will continue on an at-will basis until either the officer or ECRC terminates the officer’s employment for any reason.

For more information about the Registration Rights and Lock-Up Agreement, see the section of this joint proxy statement/prospectus entitled “Ancillary Agreements—Key Employee Agreements.”

Management and Board of Directors of NioCorp After the Transactions (page [●])

Following the Closing, it is anticipated that current officers and directors of NioCorp will remain in such roles and the two additional directors identified by GX will be appointed to the NioCorp Board, subject to NioCorp’s reasonable approval.

Yorkville Financings (page [●])

In connection with the Transactions, on January 26, 2023, NioCorp entered into the Yorkville Financing Agreements to undertake the Yorkville Financings. Once completed, the Yorkville Financings could provide NioCorp with access to up to an additional $80,360,000, before related fees and expenses payable by NioCorp.

For more information about the Yorkville Financings, see the section of this joint proxy statement/prospectus entitled “Yorkville Financings.”

GX Special Meeting of Stockholders

Date, Time and Place of the GX Stockholder Meeting (page [●])

The GX Stockholder Meeting will be held on , 2023, at , Eastern time, conducted via live webcast at the following address: https://www.cstproxy.com/gx2/2023. You will need the 12-digit meeting control number that is printed on your proxy card to enter the GX Stockholder Meeting. GX recommends that you log in at least 15 minutes before the GX Stockholder Meeting to ensure you are logged in when the GX Stockholder Meeting starts. Please note that you will not be able to attend the GX Stockholder Meeting in person.

Record Date and Voting for the GX Stockholder Meeting (page [●])

GX Stockholders will be entitled to vote or direct votes to be cast at the GX Stockholder Meeting if they owned GX Class A Shares or GX Founder Shares at the close of business on January 24, 2023, which is the record date for the GX Stockholder Meeting. GX Stockholders are entitled to one vote for each GX Class A Share or GX Founder Share that they owned as of the close of business on the record date. If a GX Stockholder’s shares are held in “street name” or are in a margin or similar account, they should contact their broker, bank or other nominee to ensure that votes related to the shares they beneficially own are properly counted. On the record date, there were 30,000,000 GX Class A Shares outstanding and 7,500,000 GX Founder Shares outstanding (all of which are held by GX’s Sponsor, officers and directors).

GX’s Sponsor, officers and directors have, for no additional consideration, agreed to vote all of their GX Founder Shares and any GX Class A Shares acquired by them in favor of the Business Combination Proposal. GX’s issued and outstanding GX Warrants do not have voting rights at the GX Stockholder Meeting.

GX Proposals for Stockholder Approval (page [●])

At the GX Stockholder Meeting, GX will ask the GX Stockholders to vote in favor of the following proposals:

●

GX Proposal No. 1 — The Business Combination Proposal: a proposal to approve the adoption of the Business Combination Agreement and the Transactions.

●

GX Proposal No. 2 — The Charter Amendment Proposal: a proposal to approve the amendment to the GX Existing Charter to remove the automatic conversion of GX Founder Shares into GX Class A Shares (such amendment, the “GX Charter Amendment”), as of immediately prior to the Closing. A copy of the GX Charter Amendment is attached to the accompanying joint proxy statement/prospectus as Annex C.

●

GX Proposal No. 3 Through No. 9 — The Charter Proposal:

seven separate non-binding, advisory proposals to approve the following material differences in the GX Proposed Charter that will replace the GX Existing Charter, as amended by the GX

Charter Amendment, as of the Closing. A copy of the GX Proposed Charter is attached to the accompanying joint proxy statement/prospectus as Annex D;

a non-binding, advisory proposal to increase the number of authorized shares of GX Class A Shares and GX Founder Shares (Proposal No. 3);

a non-binding, advisory proposal to increase the number of authorized shares of preferred stock of GX (Proposal No. 4);

a non-binding, advisory proposal to declassify the board of directors from three classes to one class (Proposal No. 5);

a non-binding, advisory proposal to provide for the election or removal of directors only upon the vote of holders of GX Class A Shares (Proposal No. 6);

●

GX Proposal No. 10 — The Adjournment Proposal: a proposal to approve a proposal to adjourn the GX Stockholder Meeting to a later date or dates, if necessary, to permit further solicitation and vote of proxies if, based upon the tabulated vote at the time of the GX Stockholder Meeting, there are not sufficient votes to approve one or more proposals presented to stockholders for a vote.

Quorum and Vote Required for the GX Proposals (page [●])

A quorum will be present at the GX Stockholder Meeting if a majority of the GX Common Stock outstanding and entitled to vote at the GX Stockholder Meeting is represented in person online or by proxy.

For more information about these proposals, see the section of this joint proxy statement/prospectus entitled “GX Special Meeting of Stockholders — Quorum and Vote Required for the GX Proposals.”

Recommendation to GX Stockholders (page [●])

The GX Board believes that each of the Business Combination Proposal, the Charter Amendment Proposal, the Charter Proposal and the Adjournment Proposal to be presented at the GX Stockholder Meeting is in the best interests of GX and its stockholders and unanimously recommends that its stockholders vote “FOR” each of these proposals.

Interests of GX Directors and Officers in the Transactions (page [●])

When GX Stockholders consider the recommendation of the GX Board in favor of approval of the Business Combination Proposal and the other proposals presented for stockholder approval in this joint proxy statement/prospectus, GX Stockholders should keep in mind that GX’s directors and officers have interests in the Transactions that are different from or in addition to (or which may conflict with) the interests of GX Stockholders. These interests include:

●

the expected appointment of Messrs. Maselli and Kehler as directors of the Combined Company;

●

the fact that GX’s Sponsor, officers and directors have agreed not to redeem any of their shares in connection with a stockholder vote to approve the Transactions;

●

that, at the Closing, GX will enter into the Registration Rights and Lock-Up Agreement, which provides for registration rights to the Sponsor and its permitted transferees;

●

the continued indemnification of current directors and officers of GX and the continuation of directors’ and officers’ liability insurance after the completion of the Transactions;

●

any founder, director or officer of GX nor does GX believe that the limitation of the application of the “corporate opportunity” doctrine in the GX Existing Charter had any impact on its search for a potential business combination;

●

the fact that the Sponsor has invested an aggregate of $9,010,000 (consisting of $25,000 for the GX Founder Shares, $8,500,000 for the GX Founder Warrants, a $250,000 working capital loan and a second working capital loan for $235,000), which means the Sponsor, following the Transactions, may experience a positive rate of return on their investment, even if other GX Public Stockholders experience a negative rate of return on their investment;

●

These interests may influence GX’s directors in making their recommendation that GX Stockholders vote in favor of the approval of the Transactions. GX’s directors were aware of and considered these interests, among other matters, in evaluating the Transactions, and in recommending to GX stockholders that they approve the Transactions. GX stockholders should take these interests into account in deciding whether to approve the Transactions.

No Appraisal or Dissenter’s Rights (page [●])

No appraisal or dissenter’s rights are available to holders of shares of GX Common Stock or GX Warrants in connection with the Transactions.

Redemption Rights of GX Stockholders (page [●])

Pursuant to the GX Existing Charter, any holders of GX Class A Shares may demand that such shares be redeemed in exchange for cash equal to their pro rata share of the aggregate amount on deposit (as of two business days prior to the Closing) in the Trust Account, including any amounts representing interest earned on the Trust Account, less taxes payable, provided that such stockholders follow the specific procedures for redemption set forth in this joint proxy statement/prospectus.

For illustrative purposes, based on funds in the Trust Account as of January 13, 2023 of approximately $303,560,016, the estimated per share redemption price would have been approximately $10.11. If a GX Public Stockholder exercises its redemption rights, then such GX Public Stockholder will be exchanging its shares of GX Class A Shares for cash and will no longer own shares of GX. Such a holder will be entitled to receive cash for its GX Class A Shares only if it properly demands redemption and delivers its shares (either physically or electronically) to GX’s transfer agent in accordance with the procedures described herein. Each redemption of GX Class A Shares by the GX Public Stockholders will decrease the amount in the Trust Account. See the section entitled “GX Special Meeting of Stockholders — Redemption Rights” for the procedures to be followed if you wish to exercise your redemption rights.

The Sponsor (page [●])

GX’s sponsor is GX Sponsor II LLC, a Delaware limited liability company. The Sponsor currently owns 7,500,000 GX Founder Shares. The Sponsor is controlled by Cooper Road, LLC (an entity controlled by Jay R. Bloom) and Dean C. Kehler, both U.S. persons. Corbin ERISA Opportunity Fund, Ltd. and ACM Alameda Special Purpose Investment Fund II LP, both Cayman Island entities, are non-controlling members of the Sponsor that collectively own approximately 11.2% interest in the Sponsor.

The parties do not believe that any of the above facts or relationships regarding the Sponsor would, by themselves, subject a business combination to regulatory review, including review by CFIUS, nor do the parties believe that if such a review were conceivable that, based solely on such facts or relationships, such business combination ultimately would be prohibited.

NioCorp Special Meeting of Shareholders (page [●])

Date, Time and Place of the NioCorp Shareholder Meeting

The NioCorp Shareholder Meeting will be held on March 6, 2023, at at 7000 S. Yosemite Street, Lower Level Conference Room, Centennial, Colorado, 80112.

Record Date and Voting for the NioCorp Shareholder Meeting (page [●])

The NioCorp Board has fixed February 1, 2023, as the record date for the purpose of determining the shareholders entitled to receive notice of and vote at the NioCorp Shareholder Meeting. Persons who are registered shareholders at the close of business on February 1, 2023, will be entitled to receive notice of, attend, and vote at the NioCorp Shareholder Meeting. On the record date, there were NioCorp Common Shares outstanding and entitled to vote at the NioCorp Shareholder Meeting. By ballot, every shareholder and proxyholder will have one vote for each share.

NioCorp Proposals for Shareholder Approval (page [●])

The purpose of the NioCorp Shareholder Meeting is to consider and vote on each of the following proposals, each of which is further described in this joint proxy statement/prospectus:

●

NioCorp Proposal No. 1 — Share Issuance Proposal: To consider and vote on the Share Issuance Proposal;

●

NioCorp Proposal No. 2 — Yorkville Equity Facility Financing Proposal: To consider and vote on the Yorkville Equity Facility Financing Proposal;

●

NioCorp Proposal No. 3 — Yorkville Convertible Debt Financing Proposal: To consider and vote on the Yorkville Convertible Debt Financing Proposal;

●

NioCorp Proposal No. 4 — Quorum Amendment Proposal: To consider and vote on the Quorum Amendment Proposal; and

●

NioCorp Proposal No. 5 — Adjournment Proposal: To consider and vote on the Adjournment Proposal.

Approval of the Share Issuance Proposal and the Quorum Amendment Proposal by NioCorp Shareholders is a condition to the consummation of the Transactions. Only business within the purposes described in the Notice of Meeting may be conducted at the NioCorp Shareholder Meeting or any adjournment thereof.

Quorum and Votes Required for the NioCorp Proposals (page [●])

Broker non-votes will not be counted as present for purposes of determining the presence of a quorum for purposes at the NioCorp Shareholder Meeting and will not be voted. Accordingly, broker non-votes will have any effect on the outcome of the votes on the matters to be acted upon at the NioCorp Shareholder Meeting.

If a NioCorp Shareholder does not specify a choice in the accompanying form of proxy card and the NioCorp Shareholder has appointed one of the management nominees named in the form of proxy, the management nominee will vote NioCorp Common Shares represented by the proxy “FOR” each of the NioCorp Proposals.

NioCorp Proposal No. 1 — Share Issuance Proposal

NioCorp Proposal No. 2 — Yorkville Equity Facility Financing Proposal

NioCorp Proposal No. 3 — Yorkville Convertible Debt Financing Proposal

NioCorp Proposal No. 4 — Quorum Amendment Proposal

NioCorp Proposal No. 5 — Adjournment Proposal

Recommendation to NioCorp Shareholders (page [●])

After careful consideration, including a review of the opinion of GenCap, information concerning GX, the Business Combination Agreement, proposed Transactions and alternatives, and consultation with management and NioCorp’s financial advisors and legal counsel, and consideration of such other matters as the NioCorp Board considered relevant, the NioCorp Board unanimously resolved (i) that the Transactions are fair to the NioCorp Shareholders and (ii) that the Transactions and entering into of the Business Combination Agreement and the other ancillaries contemplated thereby are in the best interests of NioCorp. The NioCorp Board unanimously recommends that NioCorp Shareholders vote:

●

NioCorp Proposal No. 1: “FOR” the Share Issuance Proposal;

●

NioCorp Proposal No. 2: “FOR” the Yorkville Equity Facility Financing Proposal;

●

NioCorp Proposal No. 3: “FOR” the Yorkville Convertible Debt Financing Proposal;

●

NioCorp Proposal No. 4: “FOR” the Quorum Amendment Proposal; and

●

NioCorp Proposal No. 5: “FOR” the Adjournment Proposal.

Interests of NioCorp Directors and Officers in the Transactions (page [●])

No Appraisal or Dissenter’s Rights (page [●])

No action is proposed for consideration at the NioCorp Shareholder Meeting for which the laws of British Columbia or the NioCorp Articles provide a right of a NioCorp Shareholder to dissent and obtain appraisal of or payment for such shareholder’s NioCorp Common Shares.

Material U.S. Federal Income Tax Considerations (page [●])

As discussed more fully under the section entitled “Material U.S. Federal Income Tax Considerations—Material U.S. Federal Income Tax Considerations With Respect to the Redemption and the Transactions,” the First Merger is expected to be a fully taxable transaction that does not qualify as a reorganization within the meaning of section 368(a) of the Code. Pursuant to that treatment, holders of GX stock or securities will recognize gain or loss upon any exchange of GX stock or securities for NioCorp securities in the Transactions. NioCorp also currently expects the Transactions not to result in an inversion (as defined below) for U.S. federal income tax purposes. If this determination were incorrect and the Transactions result in an inversion, adverse U.S. federal income tax consequences could apply to NioCorp and GX, and, in certain cases, NioCorp’s shareholders. All of these determinations are subject to significant uncertainty and no assurance can be given that your tax advisor will agree with these determinations or that the IRS would not assert, or that a court would not sustain, a contrary position. For a more complete analysis of U.S. federal income tax considerations relating to the Transactions, you are strongly urged to read “Material U.S. Federal Income Tax Considerations—Material U.S. Federal Income Tax Considerations With Respect to the Redemption and the Transactions” of this joint proxy statement/prospectus. You are also urged to consult your tax advisor regarding the particular federal, state, local, and non-U.S. tax consequences of the Transactions that pertain to you and your situation.

Material Canadian Federal Income Tax Considerations (page [●])

As discussed more fully under the section entitled “Material Canadian Federal Income Tax Considerations — Material Canadian Federal Income Tax Considerations With Respect to the Redemption and the Transactions,” Canadian holders whose GX stock or securities are redeemed or who acquire as beneficial owner NioCorp securities in exchange for GX stock or securities will generally realize a capital gain (or capital loss) in the taxation year of the redemption or Exchange (as applicable) to the extent the proceeds of disposition received on the redemption or Exchange (as applicable), net of any reasonable costs of disposition, exceed (or are less than) the adjusted cost base of the Canadian Resident Holder’s GX stock or securities, as determined immediately before the redemption or Exchange (as applicable).

Comparison of Shareholders’ Rights (page [●])

Upon completion of the Transactions, the rights of NioCorp Shareholders and GX Stockholders who become NioCorp Shareholders will no longer be governed by the NioCorp Articles or the GX Existing Charter and GX Bylaws, and instead will be governed by the NioCorp Amended Articles. See “Comparison of Shareholders’ Rights.”

Risk Factors (page [●])

You should read and carefully consider the risk factors set forth in the section entitled “Risk Factors” beginning on page [●] of this joint proxy statement/prospectus. You also should read and carefully consider the risk factors of NioCorp and GX contained in the documents that are incorporated by reference into this joint proxy statement/prospectus. These risks include, among others:

Risks Relating to GX and the Transactions

●

There can be no assurance that the NioCorp Common Shares or NioCorp Assumed Warrants will be approved for listing on Nasdaq or that the Combined Company will be able to comply with the continued listing standards of Nasdaq.

●

The Exchange Ratio is fixed and will not be adjusted to compensate for changes in the price of NioCorp Common Shares or in the price of GX Class A Shares.

●

Current NioCorp Shareholders and GX Stockholders will generally have a reduced ownership and voting interest in the Combined Company after the Transactions.

●

The fairness opinions obtained by the NioCorp Board and the GX Board from their respective financial advisors will not reflect changes or events that may occur after the date of the opinions.

●

Failure to complete the Transactions could negatively impact NioCorp’s or GX’s stock price and adversely affect their results of operations, cash flows and financial position.

●

The Combined Company may not realize all or any of the anticipated benefits expected as a result of the Transactions.

●

The Business Combination Agreement limits NioCorp’s ability to pursue alternatives to the Transactions or to terminate the Business Combination Agreement.

●

If NioCorp fails to consummate the Yorkville Financings, the Transactions may not be completed.

●

You may be less protected as an investor from any material issues with respect to NioCorp’s business than an investor in a public offering due to the nature of the Transactions.

●

The unaudited pro forma financial information included herein may not be indicative of what the Combined Company’s actual financial position or results of operations would have been.

●

Past performance by Trimaran Capital Partners, including GX’s management team, may not be indicative of future performance of an investment in GX or the Combined Company.

●

Changes in or a failure to comply with any laws, regulations or rules may adversely affect GX’s business, including its ability to negotiate and complete its initial business combination, investments and results of operations.

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Given the cross-border nature of the Transactions, the Combined Company will become subject to a variety of additional risks that may negatively impact the Combined Company’s operations.

●

Subsequent to the consummation of the Transactions, the Combined Company may be required to take write-downs or write-offs, or may be subject to other charges that could have a significant negative effect on the Combined Company’s financial condition.

●

The Transactions are subject to the receipt of certain approvals and conditions.

●

GX’s Sponsor, officers and directors have potential conflicts of interest in recommending that GX Stockholders vote in favor of the Transactions and the GX Proposals.

●

GX’s Sponsor, directors, officers, advisors and their affiliates may elect to purchase shares or warrants from the GX Public Stockholders, which may reduce the public “float” of GX Class A Shares.

●

GX Stockholders and NioCorp Shareholders will experience immediate dilution due to the Transactions and may experience additional dilution as a consequence of certain other transactions.

●

GX and NioCorp will incur significant costs in connection with the Transactions.

●

GX may not be able to complete an initial business combination within the prescribed time frame, in which case it would cease all operations except for the purpose of winding up.

Additional Risks Relating to Ownership of NioCorp Common Shares Following the Transactions

●

The NioCorp Common Shares do not currently trade on a national securities exchange in the United States and there is no guarantee that a market for the NioCorp Common Shares will develop in the United States to provide the NioCorp Shareholders with adequate liquidity.

●

Future issuances or sales, or the perception of future sales, of NioCorp Common Shares by existing shareholders or by NioCorp, or future dilutive issuances of NioCorp Common Shares by NioCorp, could adversely affect prevailing market prices for the NioCorp Common Shares.

●

Upon consummation of the Transactions, the rights of GX Stockholders and NioCorp Shareholders will change.

●

Canadian law and the NioCorp Amended Articles contain certain provisions, including anti-takeover provisions, that could delay or discourage takeover attempts or other actions that shareholders may consider favorable.

●

The Equity Facility is subject to satisfaction or waiver of several conditions.

Risks Relating to Redemption

●

GX does not have a specified maximum redemption threshold. The absence of such a redemption threshold may make it possible for GX to complete the Transactions even if a substantial majority of GX Stockholders redeem their shares.

●

If GX Stockholders fail to receive notice of GX’s offer to redeem the GX Class A Shares in connection with the Transactions, or fail to comply with the procedures for tendering their shares, such shares may not be redeemed.

●

There is no guarantee that a GX Stockholder’s decision to invest in NioCorp through the Transactions or, alternatively, to redeem its GX Common Stock for a pro rata portion of the Trust Account will put the stockholder in a better future economic position.

●

If third parties bring claims against GX, the proceeds held in the Trust Account could be reduced.

●

The securities in which GX invests the funds held in the Trust Account could bear a negative rate of interest, which could reduce the value of the assets held in trust such that the per-share redemption amount received by GX Public Stockholders may be less than $10.00 per share.

SELECTED HISTORICAL CONSOLIDATED FINANCIAL AND OTHER DATA

Selected Historical Financial Information of NioCorp

The information presented below is derived from NioCorp’s audited consolidated financial statements for the fiscal years ended June 30, 2022, 2021 and 2020 as of June 30, 2022 and June 30, 2021 and NioCorp’s unaudited condensed interim consolidated financial statements as of and for the three months ended September 30, 2022 and September 30, 2021. The historical results presented below are not necessarily indicative of the results to be expected for any future period. You should read carefully the following selected information in conjunction with NioCorp’s historical consolidated financial statements and accompanying notes thereto, included elsewhere in this joint proxy statement/prospectus, and the other information incorporated by reference into this joint proxy statement/prospectus.

Statement of Operations and Comprehensive Loss

(in thousands, except per share amounts)	Three Months Ended September 30,				For the Year Ended June 30,
	2022		2021		2022		2021		2020
Sales	$	—	$	—	$	—	$	—	$	—
Total operating expenses	2,082		1,256		7,796		4,092		3,432
Net loss	2,554		2,088		10,887		4,824		4,001
Loss per common share, basic and diluted	0.01		0.01		0.04		0.02		0.02

Statements of Financial Position

(in thousands)	As of September 30,				As of June 30,
	2022		2021		2022		2021
Total assets	$	23,246	$	23,289	$	22,756	$	24,470
Debt, including current portion	2,755		9,558		4,169		10,675
Shareholders’ equity	16,735		13,263		17,665		13,213

Selected Historical Financial Information of GX

GX’s historical statements of operations data for the year ended December 31, 2021 and for the period from September 24, 2020 (inception) through December 31, 2020 and the selected historical balance sheet data as of December 31, 2021 and 2020 are derived from GX’s audited financial statements included elsewhere in this joint proxy statement/prospectus. GX’s historical statements of operations data for the nine months ended September 30, 2022 and September 30, 2021 and the selected historical balance sheet data as of September 30, 2022 are derived from GX’s unaudited interim condensed financial statements included elsewhere in this joint proxy statement/prospectus. In the opinion of GX’s management, the unaudited interim condensed consolidated financial statements include all adjustments necessary to state fairly GX’s financial position as of September 30, 2022 and the results of operations for the nine months ended September 30, 2022 and 2021.

GX’s historical results are not necessarily indicative of the results to be expected in the future and GX’s results for the nine months ended September 30, 2022 are not necessarily indicative of the results that may be expected for the full year ended December 31, 2022 or any other period. You should read the following historical financial data together with the section entitled “GX’s Management’s Discussion and Analysis of Financial Condition and Results of Operations” and GX’s audited financial statements and related notes and unaudited interim condensed financial statements and related notes, included elsewhere in this joint proxy statement/prospectus.

	Year Ended December 31,			For the Period from September 24, 2020 (Inception) through December 31,			Nine Months Ended September 30,
		2021			2020		2022				2021
Statements of Operations Data:
Operating costs	$	1,391,322		$	1,450		$	5,233,040		$	793,736
Loss from operations		(1,391,322	)		(1,450	)		(5,233,040	)		(793,736	)

Other income (expense):
Change in fair value of warrant liability		12,076,667			—			6,793,333			12,233,333
Change in fair value of over-allotment option		138,932			—			—			—
Warrant transaction costs		(744,333	)		—			—			(744,333	)
Interest earned on marketable securities held in Trust Account		16,667			—			1,740,979			10,329
Unrealized loss on marketable securities held in Trust Account		—			—			—			—
Total other income, net		11,487,933			—			8,534,312			11,499,329

(Loss) Income before provision for income taxes		—			—			3,301,272			10,705,593
Provision for income taxes		—			—			(295,597	)		—
Net (loss) income	$	10,096,611		$	(1,450	)	$	3,005,675		$	10,705,593
Weighted average shares outstanding, Class A common stock		23,342,466			—			30,000,000			21,098,901
Basic and diluted (loss) net income per share, Class A common stock	$	0.33		$	—		$	0.08		$	0.37
Weighted average shares outstanding, Class B common stock		7,500,000			7,500,000			7,500,000			7,500,000
Basic and diluted net (loss) income per share, Class B common stock	$	0.33		$	(0.00	)	$	0.08		$	0.37

		As of December 31, 2021		As of December 31, 2020			As of September 30, 2022
Balance Sheets Data:
Cash	$	725,875		$	4,460	$	13,256
Marketable securities held in Trust Account	$	300,016,667		$	—	$	300,912,070
Total assets	$	301,267,911		$	101,960	$	301,390,072
Total liabilities	$	19,504,836		$	78,410	$	16,621,322
Class A common stock subject to possible redemption, 30,000,000, 30,000,000 and no shares at redemption value as of September 30, 2022, December 31, 2021 and 2020	$	300,000,000		$	—	$	300,882,070
Total stockholders’ (deficit) equity	$	(18,236,925	)	$	23,550	$	(16,113,320	)

COMPARATIVE MARKET PRICE INFORMATION

NioCorp Common Shares trade on the TSX under the symbol “NB,” on the U.S. Over-the-Counter Bulletin Board and the OTCQX under the symbol “NIOBF” and on the Frankfurt Stock Exchange as “BR3.” GX Class A Shares are currently listed on Nasdaq under the symbol “GXII.” The following table sets forth the closing sale price per share of NioCorp Common Shares reported on the OTCQX and GX Class A Shares reported on the Nasdaq Capital Market, respectively, as of September 23, 2022, the trading day before the public announcement of the execution of the Business Combination Agreement, and , , the latest practicable trading date before the mailing of this joint proxy statement/prospectus. The table also shows the estimated implied value of the merger consideration for each GX Class A share on the relevant date.

Date	NioCorp Common Shares Closing Price		GX Class A Shares Closing Price		Estimated Equivalent Per Share Value⁽¹⁾
September 23, 2022	$	0.78	$	9.80	$	8.75
,

(1)

The implied value of the merger consideration is based upon the product of the Exchange Ratio and the closing price of NioCorp Common Shares as of the applicable date.

The above table shows only historical comparisons. NioCorp Shareholders and GX Stockholders are encouraged to obtain current market quotations for shares of NioCorp Common Shares and GX Class A Shares and to review carefully and in its entirety the other information contained in, or incorporated by reference into, this joint proxy statement/prospectus. The market prices of NioCorp Common Shares and GX Class A Shares will fluctuate between the date of this joint proxy statement/prospectus and the date of completion of the Transactions. No assurance can be given concerning the market prices of NioCorp Common Shares or GX Class A Shares before or after the completion of the Transactions. Changes in the market price of NioCorp Common Shares or GX Class A Shares prior to the completion of the Transactions will affect the market value of the consideration that GX Stockholders will receive upon completion of the Transactions.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This joint proxy statement/prospectus and the other documents incorporated by reference into this joint proxy statement/prospectus contain or may contain “forward-looking statements” within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act, and “forward-looking information” within the meaning of applicable Canadian securities laws (collectively, “forward-looking statements”). Forward-looking terms such as “anticipates,” “believes,” “budgets,” “could,” “estimates,” “expects,” “forecasts,” “intends,” “may,” “might,” “outlook,” “plans,” “possible,” “potential,” “predict,” “pro forma,” “projects,” “schedule,” “should,” “target,” “will,” “would” and similar expressions are often intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Such forward-looking statements may include, but are not limited to, statements about:

●

the parties’ ability to close the proposed Transactions, including NioCorp and GX being able to receive all required regulatory, third-party and shareholder approvals for the proposed Transactions;

●

the anticipated benefits of the Transactions, including the potential amount of cash that may be available to the Combined Company upon consummation of the Transactions and the use of the net proceeds following the redemptions by GX Public Stockholders;

●

NioCorp’s expectation that its common shares will be accepted for listing on the Nasdaq Stock Market following the closing of the proposed Transactions;

●

the consummation of the Yorkville Financings;

●

the financial and business performance of NioCorp;

●

NioCorp’s anticipated results and developments in the operations of NioCorp in future periods;

●

NioCorp’s planned exploration activities;

●

the adequacy of NioCorp’s financial resources;

●

NioCorp’s ability to secure sufficient project financing to complete construction and commence operation of the Elk Creek Project;

●

NioCorp’s expectation and ability to produce niobium, scandium and titanium at the Elk Creek Project;

●

the outcome of current recovery process improvement testing, and NioCorp’s expectation that such process improvements could lead to greater efficiencies and cost savings in the Elk Creek Project;

●

the Elk Creek Project’s ability to produce multiple critical metals;

●

the Elk Creek Project’s projected ore production and mining operations over its expected mine life;

●

the completion of the demonstration plant and technical and economic analyses on the potential addition of magnetic rare earth oxides to NioCorp’s planned product suite;

●

the exercise of options to purchase additional land parcels;

●

the execution of contracts with engineering, procurement and construction companies;

●

NioCorp’s ongoing evaluation of the impact of inflation, supply chain issues and geopolitical unrest on the Elk Creek Project’s economic model;

●

the impact of health epidemics, including the COVID-19 pandemic, on NioCorp’s business and the actions NioCorp may take in response thereto; and

●

the creation of full time and contract construction jobs over the construction period of the Elk Creek Project.

The forward-looking statements speak only as of the date they are made and are based on the current beliefs and expectations of the management of NioCorp and GX, as applicable. There can be no assurance that future developments will

be those that have been anticipated. Forward-looking statements reflect material expectations and assumptions, including, without limitation, expectations and assumptions relating to: the future price of metals; the stability of the financial and capital markets; NioCorp and GX being able to receive all required regulatory, third-party and shareholder approvals for the proposed Transactions; the amount of redemptions by GX Public Stockholders; the consummation of the Yorkville Financings; and other current estimates and assumptions regarding the proposed Transactions and their benefits. Such expectations and assumptions are inherently subject to uncertainties and contingencies regarding future events and, as such, are subject to change.

Forward-looking statements involve a number of risks, uncertainties and other factors that that could cause actual outcomes and results to differ materially from those expressed or implied in those statements. Important factors that could cause actual results to differ materially from those indicated by such forward-looking statements include, without limitation, the risks and uncertainties set forth under the section entitled “Risk Factors” beginning on page [●] of this joint proxy statement/prospectus and under the heading “Risk Factors” in the documents incorporated by reference herein, including:

●

the amount of any redemptions by GX Public Stockholders being greater than expected, which may reduce the cash in trust available to NioCorp upon the consummation of the Transactions;

●

the occurrence of any event, change or other circumstances that could give rise to the termination of the Business Combination Agreement and/or payment of the termination fees;

●

the outcome of any legal proceedings that may be instituted against NioCorp or GX following announcement of the Business Combination Agreement and the Transactions;

●

the inability to complete the Transactions due to, among other things, the failure to obtain NioCorp Shareholder approval or GX Stockholder approval or the failure to consummate the Yorkville Financings;

●

the inability to complete the Yorkville Financings due to, among other things, the failure to obtain NioCorp Shareholder approval or regulatory approval;

●

the risk that the announcement and consummation of the Transactions disrupts NioCorp’s current plans;

●

the ability to recognize the anticipated benefits of the Transactions;

●

unexpected costs related to the Transactions;

●

the risks that the consummation of the Transactions is substantially delayed or does not occur, including prior to the date on which GX is required to liquidate under the terms of its charter documents;

●

NioCorp’s ability to operate as a going concern;

●

NioCorp’s requirement of significant additional capital;

●

NioCorp’s limited operating history;

●

NioCorp’s history of losses;

●

cost increases for NioCorp’s exploration and, if warranted, development projects;

●

a disruption in, or failure of, NioCorp’s information technology systems, including those related to cybersecurity;

●

equipment and supply shortages;

●

current and future offtake agreements, joint ventures, and partnerships;

●

NioCorp’s ability to attract qualified management;

●

the effects of the COVID-19 pandemic or other global health crises on NioCorp’s business plans, financial condition and liquidity;

●

estimates of mineral resources and reserves;

●

mineral exploration and production activities;

●

feasibility study results;

●

changes in demand for and price of commodities (such as fuel and electricity) and currencies;

●

changes or disruptions in the securities markets;

●

legislative, political or economic developments;

●

the need to obtain permits and comply with laws and regulations and other regulatory requirements;

●

the possibility that actual results of work may differ from projections/expectations or may not realize the perceived potential of NioCorp’s projects;

●

risks of accidents, equipment breakdowns, and labor disputes or other unanticipated difficulties or interruptions;

●

the possibility of cost overruns or unanticipated expenses in development programs;

●

operating or technical difficulties in connection with exploration, mining, or development activities;

●

the speculative nature of mineral exploration and development, including the risks of diminishing quantities or grades of reserves and resources;

●

claims on the title to NioCorp’s properties;

●

potential future litigation;

●

NioCorp’s lack of insurance covering all of NioCorp’s operations; and

●

risks related to the material weakness in NioCorp’s internal control over financial reporting, NioCorp’s efforts to remediate such material weakness and the timing of remediation.

Should one or more of these risks or uncertainties materialize, or should any of the assumptions prove incorrect, actual results may vary in material respects from those expressed or implied by these forward-looking statements. You should not place undue reliance on these forward-looking statements. All subsequent written and oral forward-looking statements concerning the Transactions or other matters addressed herein and attributable to NioCorp, GX or any person acting on their behalf are expressly qualified in their entirety by the cautionary statements above.

Neither NioCorp nor GX undertakes any obligation to update or revise any forward-looking statements to reflect events or circumstances after the date of this joint proxy statement/prospectus, whether as a result of new information, future events or otherwise, except as may be required under applicable securities laws.

RISK FACTORS

You should consider carefully the following risk factors, as well as the other information set forth in and incorporated by reference into this joint proxy statement/prospectus, before making a decision on NioCorp Proposals or the GX Proposals. As a shareholder of NioCorp following the consummation of the Transactions, you will be subject to all risks inherent in the business of NioCorp in addition to the risks relating to GX and the Transactions. The market value of your shares will reflect the performance of the business relative to, among other things, that of the competitors of NioCorp and general economic, market and industry conditions. The value of your investment may increase or may decline and could result in a loss. You should carefully consider the following factors as well as the other information contained in and incorporated by reference into this joint proxy statement/prospectus. For information regarding the documents incorporated into this joint proxy statement/prospectus by reference, see the section entitled “Where You Can Find Additional Information” beginning on page [●] of this joint proxy statement/prospectus.

Risks Relating to GX and the Transactions

Unless the context otherwise requires, all references in this “— Risks Relating to GX and the Transactions” section to “we,” “us,” or “our” refer to GX.

In connection with the closing of the Transactions, NioCorp intends to list the NioCorp Common Shares and NioCorp Assumed Warrants on Nasdaq under the symbols “NB” and “NIOBW,” respectively. NioCorp’s continued eligibility for listing may depend on the number of shares of GX Common Stock that are redeemed. If, after the Transactions, Nasdaq delists the NioCorp Common Shares or NioCorp Assumed Warrants from trading on its exchange for failure to meet Nasdaq listing standards, the Combined Company and its shareholders could face significant material adverse consequences including:

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a limited availability of market quotations for NioCorp’s securities;

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a determination that NioCorp Common Shares are a “penny stock” which will require brokers trading in NioCorp Common Shares to adhere to more stringent rules, possibly resulting in a reduced level of trading activity in the secondary trading market for NioCorp Common Shares;

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a limited amount of analyst coverage; and

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a decreased ability to issue additional securities or obtain additional financing in the future.

The Exchange Ratio is fixed and will not be adjusted to compensate for changes in the price of NioCorp Common Shares or in the price of GX Class A Shares prior to the completion of the Transactions. Because the market price of NioCorp Common Shares and GX Class A Shares may fluctuate, the value of the transaction consideration is uncertain.

Pursuant to the Business Combination Agreement, upon consummation of the First Merger, each GX Class A Share that is held by a GX Public Stockholder shall be converted into a First Merger Class A Share. In connection with the Exchange, NioCorp will exercise its unilateral option to purchase each First Merger Class A Share in exchange for 11.1829212 NioCorp Common Shares, which is the Exchange Ratio for the Transactions. As a result, each GX Public Stockholder who does not elect to exercise their redemption rights in connection with the Transactions will ultimately be issued NioCorp Common Shares.

Because the Exchange Ratio is fixed, the value of the transaction consideration will depend on the market price of NioCorp Common Shares at the time of the Exchange, which will occur immediately following the First Merger Effective Time. The Exchange Ratio will not be adjusted for changes in the market price of NioCorp Common Shares or GX Common Stock between the date of signing the Business Combination Agreement and completion of the Transactions. There will be a lapse of time between the date on which NioCorp Shareholders vote on the Share Issuance Proposal at the NioCorp Shareholder Meeting and GX Stockholders vote on the Business Combination Proposal at the GX Stockholder Meeting, and the date on which GX Stockholders entitled to receive NioCorp Common Shares actually receive those shares. The value of NioCorp Common Shares and GX Class A Shares has fluctuated since the date of the announcement of the Business Combination Agreement and will continue to fluctuate from the date of this joint proxy statement/prospectus to completion of the Transactions, and thereafter in the case of the NioCorp Common Shares. The closing sale price per share of GX Class A Shares on Nasdaq as of September 23, 2022, the last trading day before the public announcement of the execution of the Business Combination Agreement, was $9.80, and the closing sale price per share has fluctuated as high as $ and

as low as $ between that date and , , the last trading day before this joint proxy statement/prospectus. The closing sale price per share of NioCorp Common Shares on the OTCQX as of September 23, 2022, the last trading date before the public announcement of the execution of the Business Combination Agreement, was $0.78, and the closing sale price per share has fluctuated as high as $ and as low as $ between that date and , , the last trading day before this joint proxy statement/prospectus. Accordingly, at the time of the NioCorp Shareholder Meeting and the GX Stockholder Meeting, the value of the transaction consideration will not be known. Stock price changes may result from a variety of factors, including, among others, general market and economic conditions, changes in NioCorp’s operations and prospects, changes in NioCorp’s and GX’s respective cash flows and financial position, market assessments of the likelihood that the Transactions will be completed, the timing of the Transactions, and other considerations. Moreover, the issuance of additional NioCorp Common Shares in connection with the Transactions and the Yorkville Financings could depress the per share price of NioCorp Common Shares. There is no right to terminate the Business Combination Agreement and the Transactions as a result of an increase or decrease in the market price of the shares of NioCorp Common Shares or GX Class A Shares prior to the completion of the Transactions.

NioCorp Shareholders and GX Stockholders are urged to obtain current market quotations for NioCorp Common Shares and GX Class A Shares before making a voting decision with respect to the Share Issuance Proposal and the Business Combination Proposal, respectively.

Current NioCorp Shareholders and GX Stockholders will generally have a reduced ownership and voting interest in the Combined Company after the Transactions.

NioCorp may issue to GX Securityholders up to 596,549,204 NioCorp Common Shares in connection with the Transactions (including up to 175,199,102 NioCorp Common Shares issuable upon exercise of the NioCorp Assumed Warrants). Immediately following completion of the Transactions, it is expected that the current NioCorp Shareholders and the current GX Stockholders will own 42% and 58%, respectively, of the outstanding NioCorp Common Shares (assuming no redemptions by GX Stockholders and that all of the Second Merger Class B Shares are exchanged into NioCorp Common Shares and not including the potential dilutive impact of the Yorkville Financings). Please see the section entitled “Yorkville Financings — Yorkville Equity Facility Financing” for a more complete description of the Equity Facility.

NioCorp Shareholders and GX Stockholders currently have the right to vote for their respective directors and on other matters affecting their respective companies. At the completion of the Transactions, each GX Stockholder that receives NioCorp Common Shares and is not already a NioCorp Shareholder will become a NioCorp Shareholder with a percentage ownership that will be smaller than such stockholder’s percentage ownership of GX prior to the Transactions. Correspondingly, each NioCorp Shareholder will remain a NioCorp Shareholder with a percentage ownership that will generally be smaller than such shareholder’s percentage of NioCorp prior to the Transactions. As a result of these reduced ownership percentages, NioCorp Shareholders and GX Stockholders will generally have less voting power in the Combined Company after the Transactions than they now have in their respective companies.

The fairness opinions obtained by the NioCorp Board and the GX Board from their respective financial advisors will not reflect changes, circumstances, developments or events that may have occurred or may occur after the date of the opinions.

GenCap has provided a fairness opinion to the NioCorp Board stating that, as of the date of such opinion, and based upon and subject to the assumptions, limitations, and qualifications stated in such opinion, the Transactions are fair, from a financial point of view, to NioCorp Shareholders. Scalar has provided a fairness opinion to the GX Board stating that, as of the date of such opinion, and based upon and subject to the assumptions, limitations and qualifications stated in such opinion, the consideration to be received by the holders of the GX Class A Shares is fair from a financial point of view to such shareholders.

Neither the NioCorp Board nor the GX Board has obtained an updated fairness opinion as of the date of this joint proxy statement/prospectus from its respective advisors, and neither expects to receive an updated fairness opinion prior to the completion of the Transactions.

The opinions do not reflect changes, circumstances, developments or events that may have occurred or may occur after the date of the opinions, including changes in the operations and prospects of NioCorp or GX, regulatory or legal changes, general market and economic conditions and other factors that may be beyond the control of NioCorp and GX and on which the fairness opinions were based, and that may alter the value of NioCorp and GX or the prices of NioCorp Common Shares or GX Class A Shares prior to consummation of the Transactions. The value of NioCorp Common Shares and GX Class A Shares has fluctuated since, and could be materially different from its value as of, the date of the opinions, and the opinions do not address the prices at which NioCorp Common Shares or GX Class A Shares may trade since the dates of the opinions. The opinions do not speak as of the time the Transactions will be completed or as of any date other than the dates of such

opinions. Neither NioCorp nor GX anticipates asking its advisors to update their opinion, and neither of the advisors has an obligation or responsibility to update, revise or reaffirm its respective opinion based on circumstances, developments or events that may have occurred or may occur after the date of the opinion. The written opinions of NioCorp’s and GX’s advisors are attached as Annex E and Annex F, respectively, to this joint proxy statement/prospectus and are incorporated by reference herein.

Failure to complete the Transactions could negatively impact NioCorp’s or GX’s stock price and have a material adverse effect on either or both of their results of operations, cash flows and financial position.

If the Transactions are not completed for any reason, including as a result of NioCorp Shareholders or GX Stockholders failing to approve the applicable proposals, the ongoing businesses of NioCorp and GX may be materially adversely affected and, without realizing any of the benefits of having completed the Transactions, NioCorp and GX would be subject to a number of risks, including the following:

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NioCorp and GX may experience negative reactions from the financial markets, including negative impacts on their respective stock prices;

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NioCorp and GX will still be required to pay certain significant costs relating to the Transactions, such as legal, accounting, financial advisor and printing fees;

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NioCorp may be required to pay a termination fee under the terms of the Business Combination Agreement;

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the Business Combination Agreement places certain restrictions on the conduct of the respective businesses of NioCorp and GX until the earlier of the termination of the Business Combination Agreement and the Closing Date, which restrictions may have delayed or prevented the respective companies from undertaking business opportunities that, absent the Business Combination Agreement, may have been pursued;

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matters relating to the Transactions require substantial commitments of time and resources by each company’s management, which could have resulted in the distraction of each company’s management from ongoing business operations and pursuing other opportunities that could have been beneficial to the companies; and

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litigation related to any failure to complete the Transactions or related to any enforcement proceeding commenced against NioCorp or GX to perform their respective obligations under the Business Combination Agreement.

If the Transactions are not completed, any of the risks described above may materialize and they may have a material adverse effect on NioCorp’s or GX’s results of operations, cash flows, financial position and stock prices.

The Business Combination Agreement limits NioCorp’s ability to pursue alternatives to the Transactions or to terminate the Business Combination Agreement.

Upon termination of the Business Combination Agreement in specified circumstances, NioCorp must pay GX the Base Termination Fee. Such specified circumstances include, among others, termination of the Business Combination Agreement by NioCorp in order to enter into an agreement providing for a Superior Proposal, termination by GX for a change of recommendation of the NioCorp Board, or a material breach of certain of NioCorp’s covenants relating to soliciting acquisition proposals.

In addition, upon termination of the Business Combination Agreement in other specified circumstances, NioCorp is required to pay the Intentional Breach Termination Fee. Such specified circumstances include, among others, termination by GX as a result of a willful and material breach by NioCorp such that certain conditions to Closing would not be satisfied at Closing (subject to a cure period), or as a result of NioCorp’s failure to consummate the Closing of the Transactions within five business days after GX has irrevocably confirmed in writing that it is prepared to consummate the Closing and all the conditions to Closing have been satisfied.

In addition, upon termination of the Business Combination Agreement whereupon GX will be entitled to the Base Termination Fee or the Intentional Breach Termination Fee, NioCorp is also required to pay an amount equal to the sum of all documented and reasonable out-of-pocket expenses paid or payable by GX and the Sponsor in connection with the Business Combination Agreement and the Transactions, not to exceed $5,000,000. Pursuant to the Business Combination Agreement, in no event will GX be entitled to both the Base Termination Fee and the Intentional Breach Termination Fee.

These provisions could limit NioCorp’s ability to pursue alternatives to the Transactions or to terminate the Business Combination Agreement.

If NioCorp fails to consummate the Yorkville Financings, it is possible that the Transactions may not be completed.

As a condition to closing the Transactions, the Business Combination Agreement provides that NioCorp and its subsidiaries (including GX, as the surviving company of the Second Merger) will have cash in an amount equal to or greater than $15,000,000, subject to certain adjustments. NioCorp and Yorkville may not be able to consummate the financing transactions contemplated by the Yorkville Financing Agreements, which could cause NioCorp and GX to encounter difficulties in completing the Transactions with financing terms as favorable as anticipated or at all.

The scope of due diligence GX has conducted in conjunction with the Transactions may be different than would typically be conducted in the event NioCorp pursued an underwritten public offering, and you may be less protected as an investor from any material issues with respect to NioCorp’s business, including any material omissions or misstatements contained in the registration statement or this joint proxy statement/prospectus, than an investor in a public offering.

The scope of due diligence GX has conducted in conjunction with the Transactions may be different than would typically be conducted in the event NioCorp pursued an underwritten public offering. Further, raising capital and listing on Nasdaq through a business combination rather than an underwritten offering, as NioCorp is seeking to do through the Transactions, presents risks to unaffiliated investors. Such risks include a potentially different level of due diligence investigation than might be conducted by an underwriter that would be subject to potential liability for any material misstatements or omissions in a registration statement. Although GX has conducted due diligence on NioCorp and although NioCorp is currently a registrant subject to the anti-fraud requirements of the Securities Act and the Exchange Act, GX cannot assure you that this diligence revealed all material issues that may be present in NioCorp’s business, that it would be possible to uncover all material issues through a customary amount of due diligence, or that factors outside of GX’s or NioCorp’s control will not later arise. As a result, NioCorp may be forced to later write down or write off assets, restructure its operations, or incur impairment or other charges that could result in losses. Even if the due diligence successfully identifies certain risks, unexpected risks may arise and previously known risks may materialize in a manner not consistent with GX’s preliminary risk analysis. Even though these charges may be non-cash items and not have an immediate impact on NioCorp’s liquidity, the fact that NioCorp reports charges of this nature could contribute to negative market perceptions about NioCorp or its securities. Accordingly, any GX Stockholders who chooses to remain a shareholder of NioCorp following the Closing could suffer a reduction in the value of their GX shares. Such GX Stockholders are unlikely to have a remedy for such reduction in value unless they are able to successfully claim that the reduction was due to the breach by GX’s officers or directors of a duty of care or other fiduciary duty owed to them, or if they are able to successfully bring a private claim under securities laws that the proxy solicitation relating to the Transactions contained an actionable material misstatement or material omission.

The Combined Company may not realize all or any of the anticipated benefits expected as a result of the Transactions.

The success of the Transactions (if consummated) will depend, in part, on the Combined Company’s ability to realize the anticipated benefits expected from the Transactions, as further described in the sections entitled “The Transactions—NioCorp’s Reasons for the Transactions and Recommendation of the NioCorp Board” and “The Transactions—GX’s Reasons for the Transactions and Recommendation of the GX Board” of this joint proxy statement/prospectus. If the Combined Company is not successful in realizing these anticipated benefits, including the benefits of the anticipated Nasdaq listing of the NioCorp Common Shares and the anticipated acceleration of financing efforts to advance, complete construction and commence operation of the Elk Creek Project, such consequences may adversely affect the Combined Company’s business, results of operations and stock price.

If the Transactions’ benefits do not meet the expectations of investors or securities analysts, the market price of GX’s securities or, following the Closing, the Combined Company’s securities, may decline. A market for GX securities may not continue, which would adversely affect the liquidity and price of its securities.

If the perceived benefits of the Transactions do not meet the expectations of investors or securities analysts, the market price of GX’s securities prior to the Closing may decline. The market values of the Combined Company’s securities at the time of the Transactions may vary significantly from the prices of NioCorp’s or GX’s securities on the date the Business Combination Agreement was executed, the date of this joint proxy statement/prospectus, or the date on which GX Stockholders or NioCorp Shareholders vote on the Transactions.

Following the Transactions, the price of the Combined Company’s securities may fluctuate significantly due to the market’s reaction to the Transactions and general market and economic conditions. An active trading market for the

Combined Company’s securities following the Transactions may never develop or, if developed, it may not be sustained. In addition, following the Transactions, fluctuations in the price of the Combined Company’s securities could contribute to the loss of all or part of your investment. If an active market for the Combined Company’s securities develops and continues, the trading price of the Combined Company’s securities following the Transactions could be volatile and subject to wide fluctuations in response to various factors, some of which are beyond the Combined Company’s control. Any of the factors listed below could have a material adverse effect on your investment in the Combined Company’s securities and the Combined Company’s securities may trade at prices significantly below the price you paid for them. In such circumstances, the trading price of the Combined Company’s securities may not recover and may experience a further decline.

Factors affecting the trading price of the Combined Company’s securities may include:

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the realization of any of the risk factors presented in this joint proxy statement/prospectus;

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actual or anticipated fluctuations in the Combined Company’s quarterly financial results or the quarterly financial results of companies perceived to be similar to it;

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changes in the market’s expectations about the Combined Company’s operating results;

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the Combined Company’s operating results failing to meet the expectation of securities analysts of investors in a particular period;

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operating and share price performance of other companies that investors deem comparable to the Combined Company;

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the volume of NioCorp Common Shares available for public sale;

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future issuances, sales, resales or repurchases or anticipated issuances, sales, resales or repurchases of the Combined Company’s securities;

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announcements of significant acquisitions, strategic partnerships, joint ventures or capital commitments by the Combined Company or its competitors;

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the Combined Company’s ability to effectively manage growth;

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actual or anticipated variations in quarterly operating results;

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the Combined Company’s cash position;

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the Combined Company’s failure to meet the estimates and projections of the investment community or that it may otherwise provide to the public;

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changes in the market valuations of similar companies;

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overall performance of the equity markets;

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speculation in the press or investment community;

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sales of NioCorp Common Shares by it or its shareholders in the future;

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the trading volume of NioCorp Common Shares;

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changes in accounting practices;

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the ineffectiveness of the Combined Company’s internal control over financial reporting;

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disputes or other developments relating to proprietary rights, including patents, litigation matters and the Combined Company’s ability to obtain or maintain patent protection for its technologies;

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significant lawsuits, including patent or shareholder litigation;

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general political and economic conditions, including health pandemics, such as COVID-19; and

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other events or factors, many of which are beyond the Combined Company’s control.

In addition, the stock market in general, and Nasdaq in particular, have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of these companies. Broad market and industry factors may negatively affect the market price of NioCorp Common Shares, regardless of its actual operating performance. In the past, securities class action litigation has often been instituted against companies following periods of volatility in the market price of a company’s securities. This type of litigation, if instituted, could result in substantial costs and a diversion of management’s attention and resources, which would harm the Combined Company’s business, operating results or financial condition.

The unaudited pro forma financial information included herein may not be indicative of what the Combined Company’s actual financial position or results of operations would have been.

The unaudited pro forma financial information included herein is presented for illustrative purposes only and is not necessarily indicative of what the Combined Company’s actual financial position or results of operations would have been had the Transactions been completed on the dates indicated.

Past performance by Trimaran Capital Partners (“Trimaran”), including GX’s management team, may not be indicative of future performance of an investment in GX or the Combined Company.

Information regarding performance by, or businesses associated with, Trimaran and its affiliates is presented for informational purposes only. Trimaran and its affiliates are affiliates of GX’s Sponsor and are owned or controlled by Jay R. Bloom and Dean C. Kehler, GX’s Co-Chairmen and Chief Executive Officers. Past performance by Trimaran, including GX’s management team, is not a guarantee with respect to the Transactions. You should not rely on the historical record of Trimaran’s or GX’s management team’s performance as indicative of the Combined Company’s future performance, of an investment in GX or the Combined Company or the returns GX or the Combined Company will, or is likely to, generate going forward. Two members of the GX management team will be directors of the Combined Company immediately following the Transactions, but there is no assurance that their views will prevail in relation to any decisions or actions taken by the Combined Company’s board of directors. Additionally, in the course of their respective careers, members of GX’s management team have been involved in businesses and transactions that were not successful.

Changes in laws, regulations or rules, or a failure to comply with any laws, regulations or rules, may adversely affect GX’s business, including its ability to negotiate and complete its initial business combination, investments and results of operations.

GX is subject to laws, regulations and rules enacted by national, regional and local governments and Nasdaq. In particular, GX is required to comply with certain SEC, Nasdaq and other legal or regulatory requirements. Compliance with, and monitoring of, applicable laws, regulations and rules may be difficult, time consuming and costly. Those laws, regulations or rules and their interpretation and application may also change from time to time and those changes could have a material adverse effect on GX’s business, investments and results of operations. In addition, a failure to comply with applicable laws, regulations or rules, as interpreted and applied, could have a material adverse effect on GX’s business, including its ability to negotiate and complete its initial business combination (including the Transactions) and results of operations.

On March 30, 2022, the SEC issued proposed rules relating to, among other items, enhancing disclosures in business combination transactions involving special purpose acquisition companies (“SPACs”) and private operating companies; amending the financial statement requirements applicable to transactions involving shell companies; effectively limiting the use of projections in SEC filings in connection with proposed business combination transactions; increasing the potential liability of certain participants in proposed business combination transactions; and the extent to which SPACs could become subject to regulation under the Investment Company Act of 1940 (the “Investment Company Act”). These rules, if adopted, whether in the form proposed or in revised form, may materially adversely affect GX’s ability to negotiate and complete its initial business combination (including the Transactions) and may increase the costs and time related thereto.

A new 1% U.S. federal excise tax could be imposed on GX in connection with redemptions by GX of its shares in connection with a business combination or other stockholder vote pursuant to which stockholders would have a right to submit their shares for redemption (a “Redemption Event”).

On August 16, 2022, the Inflation Reduction Act of 2022 (“IR Act”) was signed into federal law. The IR Act provides for, among other things, a new U.S. federal 1% excise tax on certain repurchases (including redemptions) of stock by publicly traded domestic (i.e., U.S.) corporations and certain domestic subsidiaries of publicly traded foreign corporations.

The excise tax is imposed on the repurchasing corporation itself, not its stockholders from which shares are repurchased. The amount of the excise tax is generally 1% of the fair market value of the shares repurchased at the time of the repurchase. However, for purposes of calculating the excise tax, repurchasing corporations are permitted to net the fair market value of certain new stock issuances against the fair market value of stock repurchases during the same taxable year. In addition, certain exceptions apply to the excise tax. The Treasury has been given authority to provide regulations and other guidance to carry out, and prevent the abuse or avoidance of the excise tax. In this regard, on December 27, 2022, the Treasury and the Internal Revenue Service issued a notice announcing their intent to issue proposed regulations addressing the application of the excise tax, and describing certain rules on which taxpayers may rely prior to the issuance of such proposed regulations (the “Notice”).

Any redemption or other repurchase that occurs after December 31, 2022, in connection with a Redemption Event may be subject to the excise tax. Whether and to what extent GX would be subject to the excise tax in connection with a Redemption Event would depend on a number of factors, including (i) the fair market value of the redemptions and repurchases in connection with the Redemption Event, (ii) the structure of the business combination, (iii) the nature and amount of any “PIPE” or other equity issuances in connection with the business combination (or otherwise issued not in connection with the Redemption Event but issued within the same taxable year of the business combination) and (iv) the content of regulations and other future guidance from the Treasury. In addition, because the excise tax would be payable by GX, and not by the redeeming holder, the mechanics of any required payment of the excise tax have not been determined. The foregoing could cause a reduction in the cash available on hand to complete a business combination and in GX’s ability to complete a business combination, including the Transactions.

If GX were deemed to be an investment company for purposes of the Investment Company Act, GX may be forced to abandon its efforts to consummate an initial business combination and instead be required to liquidate. To mitigate the risk that GX might be deemed to be an investment company for purposes of the Investment Company Act, as of the date of this joint proxy statement/prospectus, GX has instructed the trustee with respect to the Trust Account to hold all funds in the Trust Account in cash until the earlier of the consummation of an initial business combination or the liquidation of GX. As a result, following the liquidation of securities in the Trust Account, GX would likely receive minimal interest, if any, on the funds held in the Trust Account, which would reduce the dollar amount GX Public Stockholders would receive upon any redemption or liquidation of GX.

On March 30, 2022, the SEC issued proposed rules relating, among other things, to circumstances in which special purpose acquisition companies (“SPAC”) such as GX could potentially be subject to the Investment Company Act of 1940 (the “Investment Company Act”) and the regulations thereunder. The SPAC Rule Proposals would provide a safe harbor for such companies from the definition of “investment company” under Section 3(a)(1)(A) of the Investment Company Act, provided that a SPAC satisfies certain criteria. To comply with the duration limitation of the proposed safe harbor, a SPAC would have a limited time period to announce and complete a de-SPAC transaction. Specifically, to comply with the safe harbor, the SPAC Rule Proposals would require a SPAC to file a report on Form 8-K announcing that it has entered into an agreement with a target company for an initial business combination no later than 18 months after the closing of its IPO. Such SPAC would then be required to complete its initial business combination no later than 24 months after the closing of its IPO.

There is currently uncertainty concerning the applicability of the Investment Company Act to a SPAC, including a company like GX, that has not consummated the business combination within 18 months after the closing of its IPO or that does not consummate its initial business combination within 24 months after such date. GX has not consummated the business combination within 18 months after the closing of its IPO, and GX can provide no assurances that it can consummate its initial business combination within 24 months of such date. As a result, it is possible that a claim could be made that GX has been operating as an unregistered investment company. If GX were deemed to be an investment company for purposes of the Investment Company Act, GX might be forced to abandon its efforts to consummate an initial business combination and instead be required to liquidate.

If GX is required to liquidate, its investors would not be able to realize the benefits of owning shares in a successor operating business, including the potential appreciation in the value of our shares and warrants following such a transaction, and our warrants would expire worthless.

In addition, even prior to the 24 month anniversary of the closing of its IPO, GX may be deemed to be an investment company. The longer that the funds in the Trust Account are held in short-term U.S. government securities or in money market funds invested exclusively in such securities, even prior to the 24-month anniversary, there is a greater risk that GX may be considered an unregistered investment company, in which case GX may be required to liquidate. The funds in the Trust Account were, following GX’s IPO, held in U.S. government treasury obligations with a maturity of 185 days or less or in money market funds investing solely in U.S. government treasury obligations and meeting certain conditions under Rule 2a-7 under the Investment Company Act. However, to mitigate the risk of GX being deemed to be an unregistered investment company (including under the subjective test of Section 3(a)(1)(A) of the Investment Company Act) and thus subject to regulation under the Investment Company Act, as of the date of this joint proxy statement/prospectus, GX has instructed Continental Stock Transfer & Trust Company, the trustee with respect to the Trust Account, to liquidate the U.S. government treasury obligations or money market funds held in the Trust Account and thereafter to hold all funds in the Trust Account in cash until the earlier of the consummation of an initial business combination and liquidation of GX. GX expects this process to be complete the week of February 6, 2023. Following such liquidation of the amounts in the Trust Account into cash, GX would likely receive minimal interest, if any, on the funds held in the Trust Account. However, interest previously earned on the funds held in the Trust Account still may be released to GX to pay its taxes, if any, and certain other expenses as permitted. As a result, any decision to liquidate the securities held in the Trust Account and thereafter to hold all funds in the Trust Account in cash would reduce the dollar amount GX Public Stockholders would receive upon any redemption or liquidation of GX.

In the event that GX may be deemed to be an investment company, GX may be required to liquidate.

GX may not be able to complete an initial business combination with certain potential target companies if a proposed transaction with the target company may be subject to review or approval by regulatory authorities pursuant to certain U.S. or foreign laws or regulations.

Certain acquisitions or business combinations may be subject to review or approval by regulatory authorities pursuant to certain U.S. or foreign laws or regulations, which may cause such acquisitions or business combinations to be delayed or ultimately prohibited. In the event that such regulatory approval or clearance is not obtained, or the review process is extended beyond the period of time that would permit an initial business combination to be consummated with GX, GX may not be able to consummate a business combination with such target.

In the United States, among other things, the U.S. Federal Communications Act prohibits foreign individuals, governments, and corporations from owning more than a specified percentage of the capital stock of a broadcast, common carrier, or aeronautical radio station licensee. In addition, U.S. law currently restricts foreign ownership of U.S. airlines. Certain mergers that may affect competition may require certain filings and review by the Department of Justice and the Federal Trade Commission, and investments or acquisitions that may affect national security are subject to review by CFIUS.

CFIUS is an interagency committee authorized to review certain transactions involving direct or indirect foreign investment in the United States by foreign persons in order to determine the effect of such transactions on the national

security of the United States. Among other things, CFIUS is empowered to require certain foreign investors to make mandatory filings, to charge filing fees related to such filings and to self-initiate national security reviews of foreign direct and indirect investments in U.S. companies if the parties to that investment choose not to file voluntarily. If CFIUS determines that an investment threatens national security, CFIUS has the power to impose restrictions on the investment or recommend that the President prohibit and/or unwind it. Whether CFIUS has jurisdiction to review an acquisition or investment transaction depends on, among other factors, the nature and structure of the transaction, the nationality of the parties, the level of beneficial ownership interest and the nature of any information or governance rights involved.

In connection with its initial business combination, GX may determine that it will submit to CFIUS review on a voluntary basis, or to proceed with the transaction without submitting to CFIUS and risk CFIUS intervention, before or after closing the transaction. CFIUS may decide to block or delay such initial business combination, or impose conditions with respect to such initial business combination, which may delay or prevent GX from consummating such initial business combination.

Outside the United States, laws or regulations may affect GX’s ability to consummate a business combination with potential target companies incorporated or having business operations in jurisdiction where national security considerations, involvement in regulated industries (including telecommunications), or in businesses relating to a country’s culture or heritage may be implicated.

U.S. and foreign regulators generally have the power to deny the ability of the parties to consummate a transaction or to condition approval of a transaction on specified terms and conditions, which may not be acceptable to us or a target. In such event, GX may not be able to consummate a transaction with that potential target.

As a result of these various restrictions, the pool of potential targets with which GX could complete an initial business combination may be limited and GX may be adversely affected in terms of competing with other SPACs that do not have similar ownership issues. Moreover, the process of government review could be lengthy. Because GX has only a limited time to complete its initial business combination, GX’s failure to obtain any required approvals within the requisite time period may require GX to liquidate. If GX liquidates, GX Public Stockholders may only receive $10.00 per share, and GX Warrants will expire worthless. This will also cause you to lose any potential investment opportunity in a target company and the chance of realizing future gains on your investment through any price appreciation in the combined company.

Given the cross-border nature of the Transactions, the Combined Company will become subject to a variety of additional risks that may negatively impact the Combined Company’s operations.

Although one of the intended benefits of the Transactions is to facilitate and accelerate growth of NioCorp, the cross-border nature of the Transactions and of NioCorp’s future operations will be subject to special considerations and risks associated with companies operating in an international setting, including any of the following:

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higher costs and difficulties inherent in managing cross-border business operations and complying with different commercial and legal requirements;

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rules and regulations regarding currency redemption;

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complex corporate withholding taxes on individuals;

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laws governing the manner in which future business combinations may be affected;

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tariffs and trade barriers;

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regulations related to customs and import/export matters;

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longer payment cycles and challenges in collecting accounts receivable;

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tax issues, such as tax law changes and differences between Canadian and U.S. tax laws;

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currency fluctuations and exchange controls;

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rates of inflation;

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employment regulations; and

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deterioration of political relations between Canada and the United States.

The Combined Company may not be able to adequately address these additional risks. If it is unable to do so, its operations might suffer, which may adversely impact its results of operations and financial condition. See “Additional Risks Relating to Ownership of NioCorp Common Shares Following Transaction” and “Risk Factors Related to NioCorp.”

Subsequent to the consummation of the Transactions, the Combined Company may be required to take write-downs or write-offs, or may be subject to restructuring, impairment or other charges that could have a significant negative effect on the Combined Company’s financial condition, results of operations and the price of NioCorp Common Shares, which could cause you to lose some or all of your investment.

Although GX has conducted due diligence on NioCorp, this diligence may not reveal all material issues that may be present with NioCorp’s business. Factors outside of NioCorp’s and outside of GX’s control may, at any time, arise. As a result of these factors, the Combined Company may be forced to later write-down or write-off assets, restructure operations, or incur impairment or other charges that could result in reporting losses. Even if GX’s due diligence successfully identified certain risks, unexpected risks may arise, and previously known risks may materialize in a manner not consistent with GX’s preliminary risk analysis. Even though these charges may be non-cash items and therefore not have an immediate impact on the Combined Company’s liquidity, the fact that the Combined Company reports charges of this nature could contribute to negative market perceptions about the Combined Company or its securities. In addition, charges of this nature may cause the Combined Company to be unable to obtain future financing on favorable terms or at all. Accordingly, any shareholders who choose to remain shareholders following the Transactions could suffer a reduction in the value of their shares. Such shareholders are unlikely to have a remedy for such reduction in value unless they are able to successfully claim that the reduction was due to the breach by GX’s officers of a duty of care or other fiduciary duty owed to them, of if they are able to successfully bring a private claim under securities laws that this joint proxy statement/prospectus constituted an actionable material misstatement or omission.

The Transactions are subject to the receipt of certain approvals, including, among others, approvals from NioCorp Shareholders as to the Share Issuance Proposal and GX Stockholders as to the Business Combination Proposal. Failure to obtain these approvals would prevent completion of the Transactions.

In order to complete the Transactions, NioCorp Shareholders must approve the Share Issuance Proposal and the Quorum Amendment Proposal and GX Stockholders must approve the Business Combination Proposal, the Charter Amendment Proposal and the Charter Proposal. There can be no assurance that these approvals will be obtained. Failure to obtain the required approvals may result in a material delay in, or the abandonment of, the Transactions. Any delay in completing the Transactions may materially adversely affect the timing and amount of cost savings and other benefits that are expected to be achieved from the Transactions.

The obligations of both NioCorp and GX to complete the Transactions are subject to a number of conditions, which, if not fulfilled, or not fulfilled in a timely manner, may result in termination of the Business Combination Agreement.

The consummation of the Transactions is subject to the satisfaction or waiver of certain customary closing conditions contained in the Business Combination Agreement, including, among other things, (i) obtaining required approvals of the Transactions and related matters by the respective shareholders of NioCorp and GX, (ii) the effectiveness of the registration statement of which this joint proxy statement/prospectus forms a part, (iii) receipt of approval for listing on Nasdaq of the NioCorp Common Shares to be issued in connection with the Transactions, (iv) receipt of approval for listing on Nasdaq of the NioCorp Assumed Warrants, (v) receipt of approval from the TSX with respect to the issuance and listing of the NioCorp Common Shares issuable in connection with the Transactions, (vi) that NioCorp and its subsidiaries (including GX, as the surviving company of the Second Merger) will have at least $5,000,001 of net tangible assets upon the consummation of the Transactions, after giving effect to any redemptions by GX Public Stockholders and after payment of underwriters’ fees or commissions, (vii) that, at Closing, NioCorp and its subsidiaries (including GX, as the surviving company of the Second Merger) will have received cash in an amount equal to or greater than $15,000,000, subject to certain adjustments (which amount may be satisfied with funds in the Trust Account or otherwise, as further described under “The Transactions—NioCorp’s Reasons for the Transactions and Recommendation of the NioCorp Board”), and (viii) the absence of any injunctions enjoining or prohibiting the consummation of the Business Combination Agreement. Each of the foregoing conditions, in addition to the other customary conditions contained in the Business Combination Agreement, may be waived by the party or parties in whose favor such closing condition is made (to the extent permitted by applicable law), except that the first, second and eighth conditions listed above may not be waived pursuant to applicable law and the third and fourth conditions may not be waived without recirculation and resolicitation.

Many of the conditions to completion of the Transactions are not within NioCorp’s or GX’s control, and neither company can predict with any certainty when or if these conditions will be satisfied. If any of these conditions are not

satisfied or waived, it is possible that the Business Combination Agreement may be terminated. Although NioCorp and GX are working to complete the Transactions as quickly as possible, these and other conditions to the completion of the Transactions may fail to be satisfied. In addition, satisfying the conditions to and completion of the Transactions may take longer, and could cost more, than NioCorp and GX expect. Neither NioCorp nor GX can predict whether and when these other conditions will be satisfied. Furthermore, the requirements for obtaining the required stock exchange clearances and approvals could delay the completion of the Transactions for a period of time or prevent them from occurring. Any delay in completing the Transactions may adversely affect the benefits that NioCorp and GX expect to achieve if the Transactions are not completed within the expected timeframe.

GX and NioCorp may waive one or more of the conditions to the Transactions.

GX and NioCorp may waive, in whole or in part, some of the conditions to its respective obligations to complete the Transactions, to the extent permitted by law and the GX Existing Charter and NioCorp Articles, as applicable. For example, it is a condition to each party’s obligations to close the Transactions that certain of the other party’s representations and warranties are true and correct in all respects as of the Closing Date, except where the failure of such representations and warranties to be true and correct, taken as a whole, does not result in a material adverse effect. However, if the GX Board or NioCorp Board determines that it is in its respective stockholders’ best interest to waive any such breach, then the GX Board or NioCorp Board may elect to waive that condition and consummate the Transactions. Neither GX nor NioCorp is able to waive the condition that its respective stockholders approve the Transactions.

GX’s Sponsor, officers and directors have potential conflicts of interest in recommending that GX Stockholders vote in favor of approval of the Transactions and the GX Proposals.

When considering the GX Board’s recommendation that GX Stockholders vote in favor of the approval of the Transactions Proposal, GX Stockholders should be aware that certain of GX’s Sponsor, executive officers and directors have financial and personal interests in the Transactions that may be different from or in addition to (and which may conflict with) the interests of GX Stockholders. These interests include:

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the beneficial ownership of the Sponsor and certain of GX’s directors and officers of an aggregate of 7,500,000 shares of GX Founder Shares and 5,666,667 Private Placement Warrants, which shares and warrants would become worthless if GX does not complete a business combination by March 22, 2023 or obtain the approval of GX Stockholders to extend the deadline for GX to consummate its initial business combination, as the Sponsor and GX’s officers and directors have waived any redemption right with respect to these shares. The Sponsor paid an aggregate of $25,000 for its GX Founder Shares, and $8,500,000 for its Private Placement Warrants, and such shares and warrants have an aggregate market value of approximately $75,525,000 and $2,720,000, respectively, based on the closing price of GX Class A Shares of $10.07 and of GX Public Warrants of $0.48 on Nasdaq on January 24, 2023, the record date for the special meeting of stockholders. Each of GX’s officers and directors is a member of the Sponsor. Cooper Road, LLC (an entity controlled by Jay R. Bloom) and Dean C. Kehler, are the managing members of the Sponsor, and as such Messrs. Bloom and Kehler have voting and investment discretion with respect to the GX Class A Shares, GX Founder Shares and GX Warrants held of record by the Sponsor;

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the expected appointment of Messrs. Maselli and Kehler as directors of the Combined Company;

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the fact that GX’s Sponsor, officers and directors have agreed not to redeem any of their shares in connection with a shareholder vote to approve the Transactions;

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that, at the Closing, GX will enter into the Registration Rights and Lock-Up Agreement, which provides for registration rights to the Sponsor and certain GX officers and directors and their permitted transferees;

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the continued indemnification of current directors and officers of GX and the continuation of directors’ and officers’ liability insurance after the Transactions;

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and officers also may become aware of business opportunities which may be appropriate for presentation to GX, and the other entities to which they owe certain fiduciary or contractual duties. Accordingly, they may have had conflicts of interest in determining to which entity a particular business opportunity should be presented. These conflicts may not be resolved in GX’s favor and such potential business opportunities may be presented to other entities prior to their presentation to GX, subject to applicable fiduciary duties under the General Corporation Law of the State of Delaware. The GX Existing Charter provides that GX renounces its interest in any corporate opportunity offered to any director or officer of GX unless such opportunity is expressly offered to such person solely in his or her capacity as a director or officer of GX and such opportunity is one GX is legally and contractually permitted to undertake and such person is legally permitted to refer such opportunity to GX. GX is not aware of any such conflict or opportunity being presented to any founder, director or officer of GX nor does GX believe that the limitation of the application of the “corporate opportunity” doctrine in the GX Existing Charter had any impact on its search for a potential business combination;

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the fact that the Sponsor has invested an aggregate of $9,010,000 (consisting of $25,000 for the GX Founder Shares, $8,500,000 for the GX Founder Warrants, a $250,000 working capital loan and a second working capital loan for $235,000), which means the Sponsor, following the Transactions, may experience a positive rate of return on their investment, even if other GX Public Stockholders experience a negative rate of return on their investment;

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the fact that the Sponsor and GX’s officers and directors will be reimbursed for out-of-pocket expenses incurred in connection with activities on its behalf, such as identifying potential target businesses and performing due diligence on suitable business combinations;

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the fact that the Sponsor and GX’s officers and directors will lose their entire investment in GX, a minimum of $9,010,000 in aggregate (consisting of $25,000 for 7,500,000 GX Founder Shares, $8,500,000 for the 5,666,667 GX Founder Warrants, the $250,000 amount outstanding under the working capital loan made by the Sponsor, the $235,000 amount outstanding under the second working capital loan made by the Sponsor, additional working capital loans made, out-of-pocket expenses to be repaid by GX and additional monthly fees due as noted above) if GX does not consummate an initial business combination by March 22, 2023 or, if approved by GX Stockholders, by the extended deadline for GX to consummate its initial business combination.

These interests may influence GX’s directors in making their recommendation that you vote in favor of the Transactions Proposal, and the transactions contemplated thereby. These interests were considered by the GX Board when it approved the Transactions.

The exercise of discretion by GX’s directors and officers in agreeing to changes to the terms of or waivers of closing conditions in the Business Combination Agreement may result in a conflict of interest when determining whether such changes to the terms of the Business Combination Agreement or waivers of conditions are appropriate and in the best interests of GX Stockholders.

In the period leading up to the Closing, other events may occur that, pursuant to the Business Combination Agreement, would require GX to agree to amend the Business Combination Agreement, to consent to certain actions or to waive rights that GX is entitled to under those agreements. Such events could arise because of changes in the course of NioCorp’s business, a request by NioCorp to undertake actions that would otherwise be prohibited by the terms of the Business Combination Agreement or the occurrence of other events that would have a material adverse effect on NioCorp’s business and would entitle GX to terminate the Business Combination Agreement. In any of such circumstances, it would be in GX’s discretion, acting through the GX Board, to grant its consent or waive its rights. The existence of the financial and personal interests of the directors described elsewhere in this joint proxy statement/prospectus may result in a conflict of interest on the part of one or more of the directors between what he or she may believe is best for GX and its stockholders and what he or she may believe is best for himself or herself or his or her affiliates in determining whether or not to take the requested action. As of the date of this joint proxy statement/prospectus, GX does not believe there will be any changes or waivers that its directors and officers would be likely to make after stockholder approval of the Transactions has been obtained. While certain changes could be made without further stockholder approval, if there is a change to the terms of the Transactions that would have a material impact on GX Stockholders, GX will be required to circulate a new or amended joint proxy statement/prospectus or supplement hereto and resolicit the vote of GX Stockholders with respect to the Business Combination Proposal.

The Sponsor may have interests in the Transactions different from the interests of GX Public Stockholders and may be incentivized to complete the Transactions, or an alternative business combination, with a less favorable company or on terms less favorable to GX Public Stockholders, rather than to liquidate.

The Sponsor has financial interests in completing the Transactions, or an alternative business combination, that are different from, or in addition to, those of GX Public Stockholders. In addition, the Sponsor may be incentivized to complete the Transactions, or an alternative business combination, with a less favorable company or on terms less favorable to GX Stockholders, rather than to liquidate, in which case the Sponsor would lose its entire investment. For example, the Sponsor is not expected to recognize taxable gain with respect to its GX Founder Shares at closing because it is retaining such shares pursuant to the Transactions (and not engaging in any taxable disposition). Rather, it will benefit from deferring any taxable gain until it ultimately exchanges its GX Founder Shares for NioCorp Common Shares (or cash). By contrast, the GX Public Stockholders generally are expected to recognize gain or loss upon exchanging their GX securities for NioCorp securities pursuant to the Transactions. For a more complete description of the tax consequences of the Transactions, please see the sections entitled “Material U.S. Federal Income Tax Considerations.” As a result, the Sponsor may have a conflict of interest in determining whether NioCorp is an appropriate business with which to effectuate the Transactions and/or in evaluating the terms of the Business Combination Agreement. However, the GX Board was aware of and considered these interests, among other matters, in evaluating and unanimously approving voting in favor of the Transactions and in recommending to GX Public Stockholders that they approve the Transactions.

GX’s Sponsor, and GX’s officers and directors have, for no additional consideration, agreed to vote in favor of the Transactions, regardless of how the GX Public Stockholders vote.

Unlike many other blank check companies in which the sponsor, officers and directors agree to vote their founder shares in accordance with the majority of the votes cast by the GX Public Stockholders in connection with an initial business combination, GX’s Sponsor, officers and directors have, for no additional consideration, agreed to vote their GX Founder Shares, as well as any GX Class A Shares purchased during or after the IPO (including in open market and privately negotiated transactions), in favor of the Transactions and the other GX Proposals. As of the record date, GX’s Sponsor, officers and directors beneficially own an aggregate of approximately 20% of the outstanding shares of GX Class A Shares and GX Founder Shares. Accordingly, it is more likely that the necessary stockholder approval will be received than would be the case if such persons agreed to vote their shares of GX Class A Shares and Founder Shares in accordance with the majority of the votes cast by the GX Public Stockholders.

GX’s Sponsor, directors, officers, advisors or their affiliates may purchase GX Class A Shares or GX Public Warrants or a combination thereof in privately negotiated transactions or in the open market either prior to or following the completion of the Transactions, although they are under no obligation to do so. However, they have no current commitments, plans or intentions to engage in such transactions and have not formulated any terms or conditions for any such transactions. None of the funds in the Trust Account will be used to purchase GX Class A Shares or GX Public Warrants in such transactions.

Such a purchase may include a contractual acknowledgement that such stockholder, although still the record holder of GX shares, is no longer the beneficial owner thereof and therefore agrees not to exercise its redemption rights. In the event that GX’s Sponsor, directors, officers, advisors or their affiliates purchase shares in privately negotiated transactions from the GX Public Stockholders who have already elected to exercise their redemption rights, such selling stockholders would be required to revoke their prior elections to redeem their shares. Any such shares purchased by GX’s Sponsor, directors, officers or advisors, or their affiliates will not be voted in favor of approving the Transactions. The purpose of any such purchases of shares would be to satisfy the closing condition in the Business Combination Agreement that requires GX to have a certain amount of cash at the Closing, where it appears that such requirement would otherwise not be met. The purpose of any such purchases of GX Public Warrants could be to reduce the number of GX Public Warrants outstanding or to vote such warrants on any matters submitted to the warrant holders for approval in connection with the Transactions. Any such purchases of GX securities may result in the completion of the Transactions, which may not otherwise have been possible. Any such purchases will be reported pursuant to Section 13 and Section 16 of the Exchange Act to the extent such purchasers are subject to such reporting requirements.

In addition, if such purchases are made, the public “float” of GX Class A Shares or GX Public Warrants and the number of beneficial holders of GX securities may be reduced, possibly making it difficult to maintain the quotation, listing or trading of GX securities on a national securities exchange.

GX Stockholders will experience immediate dilution due to the Transactions and may experience additional dilution as a consequence of certain other transactions. Depending on the extent of redemptions by GX Public Stockholders, GX Stockholders may have a minority share position following the Transactions, which may reduce the influence that current GX Stockholders have on the management of the Combined Company.

It is anticipated that, following the completion of the Transactions and assuming (for illustrative purposes) no redemptions of outstanding GX Class A Shares and that all of the Second Merger Class B Shares are exchanged into NioCorp Common Shares and not including the potential dilutive impact of the Yorkville Financings, GX’s existing stockholders, including its Sponsor, will own 58% of the Combined Company and NioCorp’s current shareholders will own 42% of the Combined Company. Please see the section entitled “Yorkville Financings — Yorkville Equity Facility Financing” for a more complete description of the Equity Facility.

If any GX Public Stockholders exercise their redemption rights, the ownership interest of the GX Stockholders in the Combined Company following the Transactions will decrease and the relative ownership interest of GX’s Sponsor will increase. In addition, if the actual facts are different than the assumptions above (which they are likely to be), the percentage ownership retained by GX’s existing stockholders in the Combined Company will be different, and non-redeeming shareholders may experience substantial dilution. Such dilution could, among other things, limit the ability of GX’s current stockholders to influence management of the Combined Company through the election of directors following the Transactions.

The table below shows possible sources of dilution and the extent of such dilution that non-redeeming GX Public Stockholders could experience following the Closing of the Transactions under three redemption scenarios and based on 279,393,227 NioCorp Common Shares outstanding and held by NioCorp Shareholders prior to the Transactions. In an effort to illustrate such potential dilution, the table below assumes (i) the issuance of NioCorp Common Shares issuable to non-redeeming GX Public Stockholders, (ii) the issuance of NioCorp Common Shares issuable to Others, (iii) the issuance of NioCorp Common Shares issuable to holders of GX Class B Common Stock, (iv) the conversion of all Earnout Shares into NioCorp Common Shares, (v) the exercise of all NioCorp Assumed GX Warrants, (vi) the exercise of all warrants, issued on February 19, 2021 to Lind Global Asset Management III, LLC (“Lind III”) and convertible into NioCorp Common Shares (the “Lind III Warrants”), (vii) the exercise of all NioCorp outstanding warrants (excluding the Lind III Warrants), (viii) the exercise of all outstanding NioCorp options held by employees at the Closing, (ix) the conversion of the remaining face value of the convertible security, dated February 16, 2021 (the “Lind III Convertible Security”), issued to Lind III, into NioCorp Common Shares, (xi) the conversion of the NioCorp Convertible Debentures into NioCorp Common Shares, (xii) the exercise of all NioCorp Financing Warrants into NioCorp Common Shares and (xiii) the sale of all NioCorp Common Shares issuable under the Equity Facility, in each case under the maximum dilution scenario for such conversion or exercise, as applicable. Furthermore, the table does not reflect the contemplated reverse stock split of the issued NioCorp Common Shares or any cash to be received upon conversion or exercise of any of NioCorp’s outstanding convertible securities, warrants or options.

	No Redemptions		50% Redemptions		Maximum Redemptions
	Shares	Ownership	Shares	Ownership	Shares	Ownership
NioCorp Common Shares outstanding prior to the Transactions	279,393,227	27.2%	279,393,227	32.4%	279,393,227	40.2%
NioCorp Common Shares issuable:
to non-redeeming GX Public Stockholders	335,487,636	32.6%	167,743,818	19.5%	2,348,413	0.3%
to Others⁽¹⁾	4,769,574	0.5%	4, 769,574	0.6%	4, 769,574	0.7%
to GX Class B	47,650,427	4.6%	47,650,427	5.5%	47,650,427	6.8%
upon the conversion of all Earnout Shares into NioCorp Common Shares	34,230,920	3.3%	34,230,920	4.0%	34,230,920	4.9%
upon the exercise of all NioCorp Assumed GX Warrants	175,199,102	17.0%	175,199,102	20.3%	175,199,102	25.2%
upon the exercise of all Lind III Warrants	8,558,000	0.8%	8,558,000	1.0%	8,558,000	1.2%
upon the exercise of all NioCorp outstanding warrants (excluding the Lind III Warrants)	9,958,253	1.0%	9,958,253	1.2%	9,958,253	1.4%
upon the exercise of all outstanding NioCorp options held by employees at the Closing	14,464,000	1.4%	14,464,000	1.7%	14,464,000	2.1%
upon the conversion of the remaining face value of the Lind III Convertible Security⁽²⁾	1,030,000	0.1%	1,030,000	0.1%	1,030,000	0.1%
upon the conversion of the NioCorp Convertible Debentures into NioCorp Common Shares⁽³⁾	19,198,500	1.9%	19,198,500	2.2%	19,198,500	2.8%
upon the exercise of all NioCorp Financing Warrants into NioCorp Common Shares⁽⁴⁾	17,278,203	1.7%	17,278,203	2.0%	17,278,203	2.5%
upon the sale of all NioCorp Common Shares issuable under the Equity Facility⁽⁵⁾	81,697,169	7.9%	81,697,169	9.5%	81,697,169	11.7%
Total	1,028,915,011	100%	861,171,193	100%	695,775,788	100%

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(1) Includes 3,343,693 NioCorp Common Shares issued to Cantor Fitzgerald, 788,455 NioCorp Common Shares issued under the Equity Facility as a commitment fee, and 637,426 NioCorp Common Shares issued to BTIG.

(2) Estimated number of NioCorp Common Shares issuable upon conversion of the remaining undisclosed face value of the Lind III Convertible Security of $815,000 (including accrued interest) based on the September 30, 2022 closing price of the NioCorp Common Shares on the TSX of CAD$1.43 and the USD:CAD exchange rate on September 29, 2022 as reported by the Bank of Canada of USD$1.00:CAD$1.3707.

(3) Estimated number of NioCorp Common Shares issuable upon conversion of the NioCorp Convertible Debentures, assuming (a) all USD$16,000,000 aggregate principal amount of the NioCorp Convertible Debentures are converted on the issuance date (prior to the accrual of any interest thereon), (b) a conversion price of USD$0.8334 (which is equal to 90% of the average of the daily VWAPs of the NioCorp Common Shares on the TSX during the five consecutive trading days ending on September 30, 2022, converted to U.S. dollars based on the USD:CAD exchange rate on September 29, 2022 as reported by the Bank of Canada of USD$1.00:CAD$1.3707, of USD$0.9260) and (c) none of the limitations on conversion of the NioCorp Convertible Debentures set forth in the term sheet for the Yorkville Convertible Debt Financing apply. This estimate of the number of NioCorp Common Shares issuable upon conversion of the NioCorp Convertible Debentures is solely for the purposes of representing possible sources of dilution. Subject to entering into a definitive agreement and consummating the Yorkville Convertible Debt Financing, the actual number of NioCorp Common Shares issued upon conversion of the NioCorp Convertible Debentures will be different due to factors outside of NioCorp’s control, including, among others, the market price of the NioCorp Common Shares around the time of any conversions and whether and, if so, when the holders thereof exercise their right to convert. See the section entitled “Yorkville Financings—Yorkville Convertible Debt Financing” for a more complete description of the Yorkville Convertible Debentures.

(4) Estimated number of NioCorp Common Shares issuable upon exercise of the NioCorp Financing Warrants, assuming (a) all of the NioCorp Financing Warrants to be issued in connection with the issuance of all USD$16,000,000 aggregate principal amount of the NioCorp Convertible Debentures are issued on the same date, (b) an exercise price of USD$0.9260 (which is equal to the greater of (i) USD$10.00 divided by the Exchange Ratio, or USD$0.8942, and (ii) the average of the daily VWAPs of the NioCorp Common Shares on the TSX during the five consecutive trading days ending on September 30, 2022, converted to U.S. dollars based on the USD:CAD exchange rate on September 29, 2022 as reported by the Bank of Canada of USD$1.00:CAD$1.3707, of USD$0.9260), (c) none of the holders elects cashless exercise and (d) none of the limitations on exercise of the NioCorp Financing Warrants set forth the term sheet for the Yorkville Convertible Debt Financing. This estimate of the number of NioCorp Common Shares issuable upon exercise of the NioCorp Financing Warrants is solely for the purposes of representing possible sources of dilution. Subject to entering into a definitive agreement and consummating the Yorkville Convertible Debt Financing, the actual number of NioCorp Common Shares issued upon exercise of the NioCorp Financing Warrants will be different due to factors outside of NioCorp’s control, including, among others, the market price of the NioCorp Common Shares around the time of each Debenture Closing (as defined herein) and whether and, if so, when the holders thereof exercise their NioCorp Financing Warrants. See the section entitled “Yorkville Financings—Yorkville Convertible Debt Financing” for a more complete description of the Yorkville Financing Warrants.

(5) Estimated number of NioCorp Common Shares issuable under the Equity Facility, assuming (a) NioCorp sells the full Commitment Amount (as defined herein) of USD$65,000,000 of NioCorp Common Shares, (b) NioCorp sells the maximum number of NioCorp Common Shares that it is permitted to in each Advance (as defined herein), subject only to the Commitment Amount and a maximum Advance (as defined herein) amount of 5,000,000 NioCorp Common Shares, (c) none of the other limitations on NioCorp’s ability to sell shares under the Equity Facility and none of the provisions that would require an adjustment to the number of NioCorp Common Shares set out in an Advance Notice (as defined herein) apply, (d) a Purchase Price (as defined herein) of USD$0.7997 (which is equal to 97% of the closing price of the NioCorp Common Shares on the TSX on September 29, 2022 of CAD$1.13, converted to U.S. dollars based on the USD:CAD exchange rate on September 29, 2022 as reported by the Bank of Canada of USD$1.00:CAD$1.3707) and (e) the issuance of the Commitment Shares (as defined herein) based on a price per share of USD$0.8244 (which is equal to the closing price of the NioCorp Common Shares on the TSX on September 29, 2022 of CAD$1.13, converted to U.S. dollars based on the USD:CAD exchange rate on September 29, 2022 as reported by the Bank of Canada of USD$1.00:CAD$1.3707). This estimate of the number of NioCorp Common Shares issuable under the Equity Facility is solely for the purposes of representing possible sources of dilution. Subject to entering into a definitive agreement and consummating the Yorkville Equity Facility Financing, the actual number of NioCorp Common Shares issued under the Equity Facility will be different due to factors outside of NioCorp’s control, including, among others, the market price of the NioCorp Common Shares around the time of each Advance. See the section entitled “Yorkville Financings—Yorkville Equity Facility Financing” for a more complete description of the Equity Facility.

Neither GX nor its stockholders will have the protection of any indemnification, escrow, price adjustment or other provisions that allow for a post-closing adjustment to be made to the total Transactions consideration in the event that any of the representations and warranties made by NioCorp in the Business Combination Agreement ultimately proves to be inaccurate or incorrect.

The representations and warranties made by NioCorp and GX to each other in the Business Combination Agreement will not survive the consummation of the Transactions. As a result, GX and its stockholders will not have the protection of any indemnification, escrow, price adjustment or other provisions that allow for a post-closing adjustment to be made to the total consideration to be received in the Transactions if any representation or warranty made by NioCorp in the Business Combination Agreement proves to be inaccurate or incorrect. Accordingly, to the extent such representations or warranties are incorrect, GX would have no indemnification claim with respect thereto and its financial condition or results of operations could be adversely affected.

GX and NioCorp will incur significant transaction and transition costs in connection with the Transactions.

GX and NioCorp have both incurred and expect to incur significant, non-recurring costs in connection with consummating the Transactions following the consummation of the Transactions. GX and NioCorp may also incur additional costs to retain key employees. If the Transactions is consummated, the funds held in the Trust Account will be released to pay (i) GX Stockholders who properly exercise their redemption rights and (ii) certain expenses incurred by NioCorp and GX in connection with the Transactions, to the extent not otherwise paid prior to the Closing. Any additional funds available for release from the Trust Account will be used for general corporate purposes of the Combined Company following the Transactions. If the Transactions is not consummated, all expenses incurred in connection with the Business Combination Agreement and Transactions will be paid by the party incurring such expenses.

Transaction expenses, payable in cash and stock, as a result of the Transactions and the Yorkville Financings, are currently estimated at approximately $20,202,000, including the reduction of the deferred underwriting fee to $5,000,000 and reduction of the BTIG advisory fees upon the consummation of the business combination. The amount of the deferred underwriting discount will not be further adjusted for any shares that are redeemed in connection with an initial business combination. The per-share amount GX will distribute to GX Public Stockholders who properly exercise their redemption rights will not be reduced by the deferred underwriting discount and after such redemptions, the per-share value of shares held by non-redeeming shareholders will reflect its obligation to pay the deferred underwriting discount.

GX’s ability to successfully effect the Transactions and the Combined Company’s ability to successfully operate the business thereafter will be largely dependent upon the efforts of certain key personnel of NioCorp, all of whom are expected to stay with the Combined Company following the Closing. The loss of such key personnel could negatively impact the operations and financial results of the combined business.

GX’s ability to successfully effect the Transactions and the Combined Company’s ability to successfully operate the business following the Closing is dependent upon the efforts of certain key personnel of NioCorp. Although, under the terms of the Business Combination Agreement, NioCorp will enter into employment agreements with certain key employees in connection with the Transactions, there can be no assurance that any of NioCorp’s key management personnel or other key employees will continue their employment in connection with the Transactions. It is possible that NioCorp will lose some key personnel, the loss of which could negatively impact the operations and profitability of the Combined Company. NioCorp’s success depends to a significant degree upon the continued contributions of senior management, certain of whom would be difficult to replace. Departure by certain of NioCorp’s officers could have a material adverse effect on NioCorp’s business, financial condition, or operating results. The services of such personnel may not continue to be available to the Combined Company.

GX Public Stockholders will not have any rights or interests in funds from the Trust Account, except under certain limited circumstances. To liquidate their investment, therefore, GX Public Stockholders may be forced to sell their GX Class A Shares or GX Public Warrants, potentially at a loss.

GX Public Stockholders will be entitled to receive funds from the Trust Account only upon the earliest to occur of: (i) GX’s completion of an initial business combination, and then only in connection with those shares of GX Class A Shares that such GX Public Stockholders properly elected to redeem, subject to the limitations described herein, (ii) the redemption of any GX Class A Shares properly submitted in connection with a shareholder vote to amend the GX Existing Charter (A) to modify the substance or timing of GX’s obligation to redeem 100% of the GX Class A Shares if GX does not complete an initial business combination by March 22, 2023 or (B) with respect to any other provision relating to shareholders’ rights or pre-initial business combination activity and (iii) the redemption of the GX Class A Shares if GX is unable to complete an initial business combination by March 22, 2023, subject to applicable law and as further described herein. In no other circumstances will a GX Public Stockholder have any right or interest of any kind in the Trust Account. Holders of GX Public Warrants will not have any right to the proceeds held in the Trust Account with respect to the warrants. Accordingly, to liquidate their investment, GX Public Stockholders may be forced to sell their GX Class A Shares or GX Public Warrants, potentially at a loss.

GX’s directors may decide not to enforce the indemnification obligations of the Sponsor, resulting in a reduction in the amount of funds in the Trust Account available for distribution to the GX Public Stockholders.

In the event that the proceeds in the Trust Account are reduced below the lesser of (i) $10.00 per share and (ii) the actual amount per share held in the Trust Account as of the date of the liquidation of the Trust Account if less than $10.00 per share due to reductions in the value of the trust assets, in each case net of the interest which may be withdrawn to pay taxes, and the Sponsor asserts that it is unable to satisfy its obligations or that it has no indemnification obligations related to a particular claim, GX’s independent directors would determine whether to take legal action against the Sponsor to enforce its indemnification obligations.

While GX currently expects that its independent directors would take legal action on its behalf against the Sponsor to enforce its indemnification obligations to GX, it is possible that GX’s independent directors, in exercising their business judgment and subject to their fiduciary duties, may choose not to do so in any particular instance if, for example, the cost of such legal action is deemed by the independent directors to be too high relative to the amount recoverable or if the independent directors determine that a favorable outcome is not likely. If GX’s independent directors choose not to enforce these indemnification obligations, the amount of funds in the Trust Account available for distribution to the GX Public Stockholders may be reduced below $10.00 per share.

GX may not have sufficient funds to satisfy indemnification claims of its directors and executive officers.

GX has agreed to indemnify its officers and directors to the fullest extent permitted by law. However, GX’s officers and directors have agreed to waive (and any other persons who may become an officer or director prior to an initial business combination will also be required to waive) any right, title, interest or claim of any kind in or to any monies in the Trust Account and not to seek recourse against the Trust Account for any reason whatsoever. Accordingly, any indemnification provided will be able to be satisfied by GX only if (i) GX has sufficient funds outside of the Trust Account or (ii) GX consummates an initial business combination. GX’s obligation to indemnify its officers and directors may discourage stockholders from bringing a lawsuit against GX’s officers or directors for breach of their fiduciary duty. These provisions also may have the effect of reducing the likelihood of derivative litigation against GX’s officers and directors, even though such an action, if successful, might otherwise benefit GX and its stockholders. Furthermore, a stockholder’s investment may be adversely affected to the extent GX pays the costs of settlement and damage awards against its officers and directors pursuant to these indemnification provisions.

GX may not be able to complete an initial business combination within the prescribed time frame, in which case it would cease all operations except for the purpose of winding up and it would redeem the GX Class A Shares and liquidate, in which case the GX Public Stockholders may only receive $10.00 per share plus accrued interest in trust, or less than such amount in certain circumstances, and the GX Public Warrants will expire worthless.

The GX Existing Charter provides that it must complete an initial business combination by March 22, 2023. GX may not be able to find a suitable target business and complete an initial business combination (including the Transactions) by such date. If GX has not completed an initial business combination prior to March 22, 2023 or obtain the approval of GX Stockholders to extend the deadline for GX to consummate its initial business combination, it will: (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten business days thereafter, redeem the GX Class A Shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account including interest earned on the funds held in the Trust Account and not previously released to GX to pay its taxes

(less up to $100,000 of interest to pay dissolution expenses), divided by the number of then outstanding GX Class A Shares, which redemption will completely extinguish the GX Public Stockholders’ rights as shareholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of GX’s remaining shareholders and the GX Board, dissolve and liquidate, subject in each case to its obligations under Delaware law to provide for claims of creditors and the requirements of other applicable law. In such case, the GX Public Stockholders may only receive $10.00 per share, and GX Public Warrants will expire worthless. In certain circumstances, the GX Public Stockholders may receive less than $10.00 per share on the redemption of their shares.

If, after GX distributes the proceeds in the Trust Account to the GX Public Stockholders, it files a bankruptcy petition or an involuntary bankruptcy petition is filed against GX that is not dismissed, a bankruptcy court may seek to recover such proceeds, and GX and its board may be exposed to claims of punitive damages.

If, after GX distributes the proceeds in the Trust Account to the GX Public Stockholders, GX files a bankruptcy petition or an involuntary bankruptcy petition is filed against GX that is not dismissed, any distributions received by GX Stockholders could be viewed under applicable debtor/creditor and/or bankruptcy laws as either a “preferential transfer” or a “fraudulent conveyance.” As a result, a bankruptcy court could seek to recover all amounts received by GX Stockholders. In addition, the GX Board may be viewed as having breached its fiduciary duty to its creditors and/or having acted in bad faith, thereby exposing itself and GX to claims of punitive damages, by paying GX Stockholders from the Trust Account prior to addressing the claims of creditors.

If, before distributing the proceeds in the Trust Account to the GX Public Stockholders, GX files a bankruptcy petition or an involuntary bankruptcy petition is filed against GX that is not dismissed, the claims of creditors in such proceeding may have priority over the claims of GX Stockholders and the per-share amount that would otherwise be received by GX Stockholders in connection with GX’s liquidation may be reduced.

If, before distributing the proceeds in the Trust Account to the GX Public Stockholders, GX files a bankruptcy petition or an involuntary bankruptcy petition is filed against GX that is not dismissed, the proceeds held in the Trust Account could be subject to applicable bankruptcy law, and may be included in GX’s bankruptcy estate and subject to the claims of third parties with priority over the claims of GX Stockholders. To the extent any bankruptcy claims deplete the Trust Account, the per-share amount that would otherwise be received by GX Stockholders in connection with GX’s liquidation may be reduced.

GX Stockholders may be held liable for claims by third parties against GX to the extent of distributions received by them upon redemption of their shares.

Under the DGCL, shareholders may be held liable for claims by third parties against a corporation to the extent of distributions received by them in a dissolution. The pro rata portion of the Trust Account distributed to the GX Public Stockholders upon the redemption of the GX Class A Shares in the event GX does not complete an initial business combination by March 22, 2023 may be considered a liquidating distribution under Delaware law. If a corporation complies with certain procedures set forth in Section 280 of the DGCL intended to ensure that it makes reasonable provision for all claims against it, including a 60-day notice period during which any third-party claims can be brought against the corporation, a 90-day period during which the corporation may reject any claims brought, and an additional 150-day waiting period before any liquidating distributions are made to shareholders, any liability of shareholders with respect to a liquidating distribution is limited to the lesser of such shareholder’s pro rata share of the claim or the amount distributed to the shareholder, and any liability of the shareholders would be barred after the third anniversary of the dissolution. However, it is GX’s intention to redeem the GX Class A Shares as soon as reasonably possible following March 22, 2023 in the event it does not complete its initial business combination and, therefore, GX does not intend to comply with the foregoing procedures.

Because GX will not be complying with Section 280, Section 281(b) of the DGCL requires GX to adopt a plan, based on facts known to GX at such time that will provide for GX’s payment of all existing and pending claims or claims that may be potentially brought against GX within the 10 years following its dissolution. However, because GX is a blank check company, rather than an operating company, and GX’s operations are limited to searching for prospective target businesses to acquire, the only likely claims to arise would be from GX’s vendors (such as lawyers, investment bankers, and auditors) or prospective target businesses. If GX’s plan of distribution complies with Section 281(b) of the DGCL, any liability of stockholders with respect to a liquidating distribution is limited to the lesser of such stockholder’s pro rata share of the claim or the amount distributed to the stockholder, and any liability of the stockholder would likely be barred after the third anniversary of the dissolution. GX cannot assure you that it will properly assess all claims that may be potentially brought against it. As such, GX Stockholders could potentially be liable for any claims to the extent of distributions received by them (but no more) and any liability of GX Stockholders may extend beyond the third anniversary of such date. Furthermore, if the

pro rata portion of the Trust Account distributed to the GX Public Stockholders upon the redemption of the GX Class A Shares in the event GX does not complete an initial business combination by March 22, 2023 is not considered a liquidating distribution under Delaware law and such redemption distribution is deemed to be unlawful (potentially due to the imposition of legal proceedings that a party may bring or due to other circumstances that are currently unknown), then pursuant to Section 174 of the DGCL, the statute of limitations for claims of creditors could then be six years after the unlawful redemption distribution, instead of three years, as in the case of a liquidating distribution.

GX or, following the Transactions, the Combined Company, may amend the terms of the GX Public Warrants in a manner that may be adverse to holders of GX Public Warrants with the approval by the holders of at least a majority of the then outstanding GX Public Warrants. As a result, the exercise price of the GX Warrants could be increased, the exercise period could be shortened and the number of GX Class A Shares purchasable upon exercise of an GX Warrant could be decreased, all without your approval.

The GX Warrants were issued in registered form under the GX Warrant Agreement between CST, as warrant agent, and GX. The GX Warrant Agreement provides that the terms of the GX Warrants may be amended without the consent of any holder to cure any ambiguity or correct any defective provision, but requires the approval by the holders of at least a majority of the then outstanding GX Public Warrants to make any change that adversely affects the interests of the registered holders of the GX Public Warrants.

Accordingly, GX may amend the terms of the GX Public Warrants in a manner adverse to a holder if holders of at least a majority of the then outstanding GX Public Warrants approve of such amendment. Although GX’s ability to amend the terms of the GX Public Warrants with the consent of at least a majority of the then outstanding GX Public Warrants is unlimited, examples of such amendments could be amendments to, among other things, increase the exercise price of the GX Public Warrants, convert the GX Public Warrants into cash or stock, shorten the exercise period or decrease the number of GX Class A Shares purchasable upon exercise of the GX Public Warrant.

In connection with the completion of the Transactions, the GX Warrants will be converted into NioCorp Assumed Warrants and NioCorp will have the right to amend such warrants on the same terms as GX may amend the GX Public Warrants.

GX or, following the Transactions, the Combined Company, may redeem your unexpired GX Warrants prior to their exercise at a time that is disadvantageous to you, thereby making your GX Warrants worthless.

GX or, following the Transactions, the Combined Company, has the ability to redeem outstanding GX Warrants at any time after they become exercisable and prior to their expiration, at a price of $0.01 per warrant, provided that the last reported sales price of GX Class A Shares equals or exceeds $18.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within a 30 trading-day period ending on the third trading day prior to the date on which GX gives proper notice of such redemption and provided certain other conditions are met. The GX Warrants will become exercisable following the Transactions and the Combined Company will not provide separate notice to the holders of GX Warrants at the time that they become exercisable (and therefore eligible for redemption). If and when the GX Warrants become redeemable by GX, GX may not exercise its redemption right if the issuance of GX Class A Shares upon exercise of the GX Warrants is not exempt from registration or qualification under applicable state blue sky laws or GX is unable to effect such registration or qualification. GX will use its best efforts to register or qualify GX Class A Shares under the blue sky laws of the state of residence in those states in which the GX Warrants were offered by GX in its IPO. Redemption of the outstanding GX Warrants could force you (i) to exercise your GX Warrants and pay the exercise price therefor at a time when it may be disadvantageous for you to do so, (ii) to sell your GX Warrants at the then-current market price when you might otherwise wish to hold your GX Warrants or (iii) to accept the nominal redemption price which, at the time the outstanding GX Warrants are called for redemption, is likely to be substantially less than the market value of your GX Warrants. None of the Private Placement Warrants will be redeemable by GX so long as they are held by the Sponsor or its permitted transferees.

In connection with the completion of the Transactions, the GX Warrants will be converted into NioCorp Assumed Warrants and the Combined Company will have the right to redeem such warrants on the same terms as they may be redeemed by GX at any time following the completion of the Transactions.

Because each GX Public Unit contains one-third of one redeemable warrant and only a whole warrant may be exercised, the GX Public Units may be worth less than units of other blank check companies.

Each GX Public Unit contains one-third of one redeemable warrant. No fractional warrants will be issued upon separation of the GX Public Units and only whole warrants will trade. Accordingly, unless you purchase at least three GX

Public Units, you will not be able to receive or trade a whole warrant. This is different from other offerings similar to GX’s IPO whose units include one share of common stock and one warrant to purchase one whole share. GX has established the components of the GX Public Units in this way in order to reduce the dilutive effect of the warrants upon completion of an initial business combination since the warrants will be exercisable in the aggregate for one half of the number of shares compared to units that each contain a warrant to purchase one whole share, thus making GX a more attractive business combination partner for target businesses. Nevertheless, this unit structure may cause GX’s units to be worth less than if they included a warrant to purchase one whole share.

GX and its directors are, or may in the future be, subject to demands, claims, suits and other legal proceedings, including challenging the Transactions, that may result in adverse outcomes, including preventing the consummation of the Transactions or from becoming effective within the expected time frame.

Transactions such as the one proposed are frequently subject to demands, litigation or other legal proceedings, including demands by GX Stockholders on the GX Board seeking disclosure of material information that was allegedly omitted from the registration statement. GX and its directors are, or may in the future be, subject to demands, claims, suits and other legal proceedings, including challenging the Transactions. Such demands, claims, suits and legal proceedings are inherently uncertain, and their results cannot be predicted with any certainty. An adverse outcome in such legal proceedings, as well as the costs and efforts of a defense even if successful, can have an adverse impact on GX or NioCorp because of legal costs, diversion or distraction of management or other personnel, negative publicity and other factors. In addition, it is possible that a resolution of one or more legal proceedings could result in reputational harm, liability, penalties, sanctions, as well as judgments, consent decrees or orders, which could in the future materially and adversely affect GX’s or NioCorp’s business, financial condition and results of operations.

The GX Board has received a demand from a putative GX Stockholder, dated November 21, 2022 (the “Demand”), alleging that this joint proxy statement/prospectus is materially misleading and/or omits material information with respect to the Transactions. The Demand seeks the issuance of corrective disclosures in an amendment or supplement to this joint proxy statement/prospectus.

The GX Existing Charter requires, to the fullest extent permitted by law, that derivative actions brought in GX’s name, actions against its directors, officers, other employees or stockholders for breach of fiduciary duty and other similar actions may be brought only in the Court of Chancery in the State of Delaware and, if brought outside of Delaware, the stockholder bringing the suit will be deemed to have consented to service of process on such stockholder’s counsel except any action (A) as to which the Court of Chancery in the State of Delaware determines that there is an indispensable party not subject to the jurisdiction of the Court of Chancery (and the indispensable party does not consent to the personal jurisdiction of the Court of Chancery within ten days following such determination), (B) which is vested in the exclusive jurisdiction of a court or forum other than the Court of Chancery, (C) for which the Court of Chancery does not have subject matter jurisdiction, or (D) any action arising under the Securities Act, as to which the Court of Chancery and the federal district court for the District of Delaware will have concurrent jurisdiction. Any person or entity purchasing or otherwise acquiring any interest in shares of GX’s capital stock will be deemed to have notice of and consented to the forum provisions in the GX Existing Charter. This choice of forum provision may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with GX or any of its directors, officers, other employees or stockholders, which may discourage lawsuits with respect to such claims, although GX Stockholders will not be deemed to have waived its compliance with federal securities laws and the rules and regulations thereunder. GX cannot be certain that a court will decide that this provision is either applicable or enforceable, and if a court were to find the choice of forum provision contained in the GX Existing Charter to be inapplicable or unenforceable in an action, GX may incur additional costs associated with resolving such action in other jurisdictions, which could harm its business, operating results and financial condition.

The GX Existing Charter provides that the exclusive forum provision will be applicable to the fullest extent permitted by applicable law. Section 27 of the Exchange Act creates exclusive federal jurisdiction over all suits brought to enforce any duty or liability created by the Exchange Act or the rules and regulations thereunder. As a result, the exclusive forum provision does not apply to suits brought to enforce any duty or liability created by the Exchange Act or any other claim for which the federal courts have exclusive jurisdiction.

Additional Risks Relating to Ownership of NioCorp Common Shares Following the Transactions

If GX’s Adjournment Proposal is not approved and an insufficient number of votes have been obtained to approve the GX Proposals, or if NioCorp’s Adjournment Proposal is not approved and an insufficient number of votes have been obtained to approve the NioCorp Proposals, the GX Board and the NioCorp Board may not have the ability to adjourn the GX Stockholder Meeting or the NioCorp Shareholder Meeting, respectively, to a later date in order to solicit further votes, and, therefore, the necessary approvals may not be obtained, and, therefore, the Transactions may not be consummated.

The GX Adjournment Proposal, if adopted by GX Stockholders, will allow the GX Board to adjourn the GX Stockholder Meeting to a later date or dates to permit further solicitation of proxies with respect to the GX Proposals. The NioCorp Adjournment Proposal, if adopted by NioCorp Shareholders, will allow the NioCorp Board to adjourn the NioCorp Shareholder Meeting to a later date or dates to permit further solicitation of proxies with respect to the NioCorp Proposals. If the respective Adjournment Proposal is not approved by the GX Stockholders or the NioCorp Shareholders, the GX Board and the NioCorp Board, respectively, may not be able to adjourn the GX Stockholder Meeting or the NioCorp Shareholder Meeting (as applicable) to a later date in the event that, based on the tabulated votes, there are not sufficient votes at the time of the applicable meeting to approve one or more of the proposals presented at the such meeting. In such event, GX or NioCorp may not be able to obtain the requisite shareholder approvals, and the Transactions may not be consummated.

The NioCorp Common Shares do not currently trade on a national securities exchange in the United States and there is no guarantee that a market for the NioCorp Common Shares will develop to provide the NioCorp Shareholders with adequate liquidity.

The NioCorp Common Shares are currently listed only on the TSX and on the OTC Markets trading platform under the symbol “NIOBF.” Prior to completion of the Transactions, the NioCorp Common Shares will not have been listed on a nationally-recognized stock exchange in the United States. If an active trading market does not develop in the United States, NioCorp Shareholders may have difficulty selling any of the NioCorp Common Shares over a U.S. exchange. The extent to which investor interest in NioCorp will lead to the development of an active trading market on the Nasdaq or otherwise, or how liquid that market might become, is uncertain. In addition, redemptions of GX Class A Shares by the GX Public Stockholders may impact liquidity in the NioCorp Common Shares.

The historical trading price of the NioCorp Common Shares on the TSX may not be indicative of prices that will prevail in the United States trading market or otherwise following completion of the Transactions. Listing of the NioCorp Common Shares on the Nasdaq in addition to the TSX may increase price volatility on the TSX and also result in volatility of the trading price on the Nasdaq because trading will be in two markets, which may result in less liquidity on both exchanges. In addition, different liquidity levels, volumes of trading, currencies and market conditions on the two exchanges may result in different prevailing trading prices.

Future sales, or the perception of future sales, of NioCorp Common Shares by existing shareholders or by NioCorp, or future dilutive issuances of NioCorp Common Shares by NioCorp, could adversely affect prevailing market prices for the NioCorp Common Shares.

Subject to compliance with applicable securities laws, sales of a substantial number of NioCorp Common Shares in the public market could occur at any time. These sales, or the market perception that the holders of a large number of NioCorp Common Shares or securities convertible into NioCorp Common Shares intend to sell NioCorp Common Shares, could reduce the prevailing market price of the NioCorp Common Shares. The effect, if any, that future public sales of these securities or the availability of these securities for sale will have on the market price of the NioCorp Common Shares is uncertain. If the market price of the NioCorp Common Shares were to drop as a result, this might impede NioCorp’s ability to raise additional capital and might cause remaining shareholders to lose all or part of their investment.

Following the consummation of the Transactions, GX, the Sponsor, in its capacity as a shareholder of GX, as well as the pre-Closing directors and officers of NioCorp will be subject to “lock-up” restrictions, as described under “Ancillary Agreements – Registration Rights and Lock-Up Agreement”. The provisions of these “lock-up” restrictions may be waived under limited circumstances and allow NioCorp to, among other things, issue additional NioCorp Common Shares, or allow the directors and officers of NioCorp or its shareholders to sell their NioCorp Common Shares at any time. There are no pre-established conditions for the grant of such a waiver by the relevant parties, and any decision by the applicable parties to waive those conditions may depend on a number of factors, which might include market conditions, the performance of the NioCorp Common Shares in the market and NioCorp’s financial condition at that time. If the “lock-up” restrictions of NioCorp are waived, additional NioCorp Common Shares will be issued, and if the “lock-up” restrictions of the applicable shareholders or the directors and officers of NioCorp are waived, additional NioCorp Common Shares will be available for sale into the public market, subject to applicable securities laws, which, in both cases, could reduce the prevailing market price for the NioCorp Common Shares.

The NioCorp Amended Articles will permit NioCorp to issue an unlimited number of NioCorp Common Shares without seeking shareholder approval.

The NioCorp Amended Articles will permit NioCorp to issue an unlimited number of NioCorp Common Shares. It is anticipated that NioCorp will, from time to time, issue additional NioCorp Common Shares in the future. Subject to the requirements of the BCBCA, the Nasdaq and the TSX, NioCorp will not be required to obtain the approval of the NioCorp Shareholders for the issuance of additional NioCorp Common Shares. Any further issuances of NioCorp Common Shares will result in immediate dilution to existing shareholders and may have an adverse effect on the value of their shareholdings. See “Description of Share Capital – NioCorp Common Shares.”

Upon consummation of the Transactions, the rights of holders of NioCorp Common Shares arising under the BCBCA as well as the NioCorp Amended Articles will differ from and may be less favorable to the rights of holders of GX Common Stock arising under Delaware law as well as the GX Existing Charter and the GX Bylaws.

Upon consummation of the Transactions, the rights of holders of NioCorp Common Shares will arise under the NioCorp Amended Articles as well as the BCBCA. The NioCorp Amended Articles and the BCBCA contain provisions that differ in some respects from those in the GX Existing Charter, GX Bylaws and Delaware law and, therefore, some rights of holders of NioCorp Common Shares could differ from the rights that holders of GX Common Stock currently possess. For instance, (i) for material corporate transactions (such as mergers and amalgamations, other extraordinary corporate transactions or amendments to the NioCorp Articles), the BCBCA generally requires a two-thirds majority vote by shareholders, whereas

Delaware law generally requires only a majority vote, and (ii) under the BCBCA, holders of 5% or more of the NioCorp’s shares that carry the right to vote at a meeting of shareholders can requisition a special meeting of shareholders, whereas such right does not exist under Delaware law. In addition, there are differences between the NioCorp Amended Articles and the GX Existing Charter and the GX Bylaws. For a more detailed description of the rights of holders of NioCorp Common Shares and how they may differ from the rights of holders of GX Common Stock, please see “Comparison of Shareholders’ Rights.”

Canadian law and the NioCorp Amended Articles contain certain provisions, including anti-takeover provisions, that limit the ability of shareholders to take certain actions and could delay or discourage takeover attempts that shareholders may consider favorable.

Provisions in the NioCorp Amended Articles, as well as certain provisions under the BCBCA and applicable Canadian laws, may discourage, delay or prevent a merger, acquisition or other change in control of NioCorp that shareholders may consider favorable, including transactions in which they might otherwise receive a premium for their NioCorp Common Shares. For instance, the NioCorp Amended Articles will contain provisions that establish certain advance notice procedures for nomination of candidates for election as directors at shareholders’ meetings. See “Comparison of Shareholders’ Rights – Shareholder Nominations of Persons for Election as Directors.”

Limitations on the ability to acquire and hold NioCorp Common Shares may also be imposed by the Competition Act (Canada). This legislation permits the Commissioner of Competition, or Commissioner, to review any acquisition or establishment, directly or indirectly, including through the acquisition of shares, of control over or of a significant interest in NioCorp. Moreover, a non-Canadian must file an application for review with the Minister responsible for the Investment Canada Act and obtain approval of the Minister prior to acquiring control of a “Canadian business” within the meaning of the Investment Canada Act, where prescribed financial thresholds are exceeded. See “Description of Securities – NioCorp Common Shares – Exchange Controls.”

Any of these provisions could limit the price that investors might be willing to pay in the future for the NioCorp Common Shares, thereby depressing the market price for the NioCorp Common Shares.

The Equity Facility is subject to satisfaction or waiver of several conditions.

Completion of the Equity Facility is subject to the satisfaction of a number of conditions precedent, certain of which are outside of NioCorp’s control, including, but not limited to, the approval of the Yorkville Equity Facility Financing Proposal, and other customary conditions. A substantial delay in obtaining satisfactory approvals and/or the imposition of unfavorable terms or conditions in the approvals to be obtained could result in the termination of the Yorkville Equity Facility Financing Agreement. There can be no certainty, nor can NioCorp provide any assurance, that these conditions will be satisfied or, if satisfied, when they will be satisfied. If the Equity Facility is not completed: (i) certain costs related to the Yorkville Equity Facility Financing Agreement, such as legal, accounting and financial advisory fees, must be paid by NioCorp even if the Equity Facility is not completed; (ii) NioCorp may not be successful in finding another business opportunity that is of equal or greater benefit to NioCorp; and (iii) the time and attention of NioCorp’s management will have been diverted away from the conduct of NioCorp’s business.

The NioCorp Common Shares to be issued under the Yorkville Equity Facility Financing Agreement may dilute NioCorp Shareholders.

If the Equity Facility is approved by NioCorp Shareholders, a significant number of the NioCorp Common Shares would become potentially issuable to Yorkville under the Yorkville Equity Facility Financing Agreement. Additionally, the lower the market or trading price of the NioCorp Common Shares in the future, the greater the number of NioCorp Common Shares potentially issuable to Yorkville under the Yorkville Equity Facility Financing Agreement would become. Factors both within and beyond NioCorp’s control could cause the market or trading price of the NioCorp Common Shares to decline, even significantly, in the future. As a result, existing NioCorp Shareholders will have their positions significantly diluted by the potential increase in additional outstanding NioCorp Common Shares due to the issuance of NioCorp Common Shares to Yorkville under the Yorkville Equity Facility Financing Agreement.

The issuance and future sale of NioCorp Common Shares could adversely affect the market price.

If the Equity Facility is completed, and subject to the terms of the Yorkville Equity Facility Financing Agreement, the potential issuance of NioCorp Common Shares to Yorkville thereunder, the sale of NioCorp Common Shares in the public market from time to time, and any disclosures to be made by NioCorp relating thereto, could depress the market price for NioCorp Common Shares.

The Investors may engage in resales or other hedging strategies.

If the Equity Facility is completed, the Investors may engage in resales or other hedging strategies to reduce or eliminate investment risks associated with a drawdown. Any such transactions could have a significant effect on the market price of the NioCorp Common Shares.

If the Standby Equity Purchase Agreement is terminated or the Equity Facility is not consummated, there could be a potential material adverse effect on NioCorp.

If the Equity Facility is not completed, the market price of the NioCorp Common Shares may decline to the extent that the market price reflects a market assumption that the Equity Facility will be completed. If the Equity Facility is not completed and the NioCorp Board decides to seek an equity line of credit from another strategic investor, there can be no assurance that it will be able to find an investor of equal interest as the Investors or a party that would be willing to consummate a transaction on terms as favorable as the Equity Facility. Failure by NioCorp to have access to financing on the terms and conditions of the Equity Facility may be materially adverse to NioCorp.

There is a potential for Yorkville to exercise significant influence on the operations of NioCorp because of the potential increase in voting power if the Equity Facility is approved.

If NioCorp Shareholders approve the Yorkville Equity Facility Financing Proposal, and NioCorp Common Shares under the Equity Facility are subscribed for and held, and not re-sold, by Yorkville, Yorkville’s voting power in NioCorp will increase, subject to certain ownership limitations set forth in the Yorkville Equity Facility Financing Agreement. Accordingly, Yorkville may potentially have the ability to exercise an increased influence on NioCorp’s decisions as compared to other NioCorp Shareholders.

NioCorp’s Chief Executive Officer, President and Executive Chairman, Mark Smith, also holds certain management positions and directorships of other companies and may allocate his time to such other businesses, thereby causing conflicts of interest in their determination as to how much time to devote to NioCorp’s affairs. This could have a negative impact on NioCorp’s operations.

NioCorp’s Chief Executive Officer, President and Executive Chairman, Mark Smith, is engaged in other business endeavors which may result in a conflict of interest in allocating his time between NioCorp’s operations and his other businesses. Although Mr. Smith is employed with NioCorp on a full-time basis, he is permitted to participate in certain other business activities, including his service as the Chief Executive Officer of IBC Advanced Alloys Corp., and the amount of time he dedicates to each company is not easily quantifiable. Accordingly, although Mr. Smith’s primary occupation is his service to NioCorp, he also holds certain management positions and directorships of other companies and may allocate his time to such other businesses and is entitled to compensation in connection with those activities, thereby causing potential conflicts of interest in his determination as to how much time to devote to NioCorp’s affairs. Mr. Smith may also have competitive fiduciary obligations and pecuniary interests relating to his other business ventures that conflict with NioCorp’s interests. Although NioCorp is not aware of any material conflicts of interest involving Mr. Smith at the present time, there is a possibility that these additional activities may create such a conflict between their interests and NioCorp’s, which could result in a negative impact on NioCorp’s operations.

NioCorp may be a “passive foreign investment company” for the current taxable year and for one or more future taxable years, which may result in materially adverse U.S. federal income tax consequences for U.S. investors.

If NioCorp is a passive foreign investment company (“PFIC”) for any taxable year, or portion thereof, that is included in the holding period of a U.S. holder of NioCorp Common Shares or NioCorp Assumed Warrants, such U.S. holder may be subject to certain adverse U.S. federal income tax consequences and additional reporting requirements. Although NioCorp believes it was classified as a PFIC during its taxable years ended June 30, 2022 and June 30, 2021, based on the current composition of its income and assets, as well as current business plans and financial expectations, NioCorp does not currently expect to be treated as a PFIC for the taxable year in which the Transactions occur or any foreseeable future taxable years. However, this conclusion is a factual determination that must be made annually at the close of each taxable year and, thus, is subject to change. In addition, it is possible notwithstanding NioCorp’s conclusion that the IRS could assert, and that a court could sustain, a determination that NioCorp is a PFIC. Accordingly, there can be no assurance that NioCorp will not be treated as a PFIC for any taxable year. For a more detailed description of the possibility of NioCorp (or its subsidiaries) qualifying as a PFIC and the consequences thereof, see the section entitled “Material U.S. Federal Income Tax Considerations With Respect to the Redemption and the Transactions — Tax Considerations for U.S. Holders in Respect of Ownership of NioCorp Common Shares and NioCorp Assumed Warrants.” Each holder of NioCorp Common Shares or NioCorp Assumed Warrants should consult its own tax advisors regarding the PFIC rules and the U.S. federal income tax consequences of the acquisition, ownership, and disposition of such securities.

The Transactions could result in NioCorp becoming subject to materially adverse U.S. federal income tax consequences.

Section 7874 and related sections of the Code provide for certain adverse tax consequences when the stock of a U.S. corporation is acquired by a non-U.S. corporation in certain transactions in which former shareholders of the U.S. corporation come to own 60% or more of the stock of the non-U.S. corporation (by vote or value, and applying certain specific counting and ownership rules). These adverse tax consequences include (i) potential additional required gain recognition by the U.S. corporation, (ii) treatment of certain payments to the non-U.S. corporation that reduce gross income as “base erosion payments,” (iii) an excise tax on certain options and stock-based compensation of the U.S. corporation, (iv) disallowance of “qualified dividend” treatment for distributions by the non-U.S. corporation, and (v) if former shareholders of the U.S. corporation come to own 80% or more of the stock of the non-U.S. corporation, treatment of the non-U.S. corporation as a U.S. corporation subject to U.S. federal income tax on its worldwide income (in addition to any tax imposed by non-U.S. jurisdictions). If the Transactions result in the application of any of these, or any other, adverse tax consequences, NioCorp could incur significant additional tax costs. While NioCorp currently does not believe the Transactions will cause such adverse tax consequences as a result of section 7874 and related sections of the Code, this determination is subject to significant legal and factual uncertainty. NioCorp has not sought and will not seek any rulings from the IRS as to the tax treatment of any of the Transactions, and the closing of the Transactions is not conditioned upon receiving a ruling from any tax authority or opinion from any tax advisor in regards to any particular tax treatment. Further, there can be no assurance that your tax advisor, the IRS, or a court, will agree with the position that NioCorp is not subject to these adverse tax consequences. For further detail regarding the application of section 7874 of the Code to the Transactions, see the section entitled “Material U.S. Federal Income Tax Considerations—Material U.S. Federal Income Tax Considerations With Respect to the Redemption and the Transactions—Inversion Considerations and Tax Residence of NioCorp for U.S. Federal Income Tax Purposes.”

Risk Factors Related to NioCorp

NioCorp’s business is and will be subject to the risks described above. In addition, NioCorp is, and will continue to be, subject to the risks described in NioCorp’s Annual Report on Form 10-K for the fiscal year ended June 30, 2022, as such risks may be updated or supplement in NioCorp’s subsequently filed Quarterly Reports on Form 10-Q and Current Reports on Form 10-K, each of which are filed with the SEC and applicable Canadian securities regulatory authorities and incorporated by reference in this joint proxy statement/prospectus. See the section entitled “Where You Can Find Additional Information.”

Risks Relating to Redemption

The GX Existing Charter does not provide a specified maximum redemption threshold, except that GX will only redeem its GX Class A Shares so long as (after such redemption) the net tangible assets of NioCorp and its subsidiaries (including GX, as the surviving company of the Second Merger) will be at least $5,000,001 either immediately prior to or upon consummation of the Transactions and after payment of underwriter’s fees and commissions (such that GX is not subject to the SEC’s “penny stock” rules). As a result, GX may be able to complete the Transactions even if a substantial majority of the GX Public Stockholders redeem their shares. In the event the aggregate cash consideration GX would be required to pay for all GX Class A Shares that are validly submitted for redemption plus any amount required to satisfy cash conditions pursuant to the terms of the Business Combination Agreement exceed the aggregate amount of cash available to GX, GX will not complete the Transactions or redeem any shares, all GX Class A shares submitted for redemption will be returned to the holders thereof, and GX instead may search for an alternate business combination.

GX will comply with the proxy rules when conducting redemptions in connection with the Transactions. Despite GX’s compliance with these rules, if a stockholder fails to receive GX’s proxy materials, such stockholder may not become aware of the opportunity to redeem its shares. In addition, proxy materials that GX will furnish to holders of the GX Class A Shares in connection with the Transactions will describe the various procedures that must be complied with in order to validly redeem GX Class A Shares. For example, GX may require the GX Public Stockholders seeking to exercise their redemption rights, whether they are record holders or hold their shares in “street name,” to either tender their certificates to GX’s transfer agent up to two business days prior to the vote on the proposal to approve the Transactions in the event GX distributes proxy materials, or to deliver their shares to the transfer agent electronically. In the event that a stockholder fails to comply with these or any other procedures, its shares may not be redeemed.

If a stockholder or a “group” of stockholders are deemed to hold in excess of 15% of the issued and outstanding GX Class A Shares, such stockholder or group will lose the ability to redeem all such shares in excess of 15% of the issued and outstanding GX Class A Shares.

The GX Existing Charter provides that a GX Stockholder, individually or together with any affiliate of such stockholder or any other person with whom such stockholder is acting in concert or as a “group” (as defined under Section 13 of the Exchange Act), will be restricted from seeking redemption rights with respect to an aggregate of more than 15% of the shares of GX Common Stock sold in the IPO without GX’s prior consent, which GX refers to as the “Excess Shares.” However, GX will not be restricting its stockholders’ ability to vote all of their shares (including Excess Shares) for or against the Transactions. The inability of a stockholder to redeem an aggregate of more than 15% of the shares of GX Common Stock sold in the IPO will reduce its influence over GX’s ability to consummate its initial business combination and such stockholder could suffer a material loss on its investment in GX if it sells such excess shares in open market transactions. Additionally, the stockholder will not receive redemption distributions with respect to the Excess Shares if GX completes the Transactions. As a result, such stockholders will continue to hold that number of shares exceeding 15% and, in order to dispose of such shares, would be required to sell its shares in open market transactions, potentially at a loss.

GX can give no assurance as to the price at which GX Stockholders may be able to sell, in the future, the securities issued to or otherwise held by GX Stockholders following a business combination, including the Transactions. A stockholder that does not redeem its GX Common Stock will, following the Transactions, bear the risk of ownership of the NioCorp Common Shares issued in exchange for GX Common Stock, and there can be no assurance that a shareholder will be able to sell such NioCorp Common Shares in the future for a greater amount than the redemption price set forth herein. Similarly, events following the consummation of the Transactions may cause an increase in the public trading price of the NioCorp Common Shares issued to GX Stockholders following the Transactions.

Furthermore, all outstanding GX Public Warrants converted into NioCorp Assumed Warrants in connection with the Transactions will continue to be outstanding notwithstanding the actual redemptions. An aggregate value of the outstanding NioCorp Assumed Warrants of approximately $7,520,000 (based on the closing price of the GX Public Warrants of $0.48 on the Nasdaq Global Market as of January 24, 2023, the record date for the GX Stockholders Meeting) may be retained by the redeeming stockholders assuming maximum redemptions. The potential for the issuance of a substantial number of NioCorp Common Shares upon exercise of these NioCorp Assumed Warrants could make the Combined Company less attractive to investors. Any such issuance will increase the number of issued and outstanding NioCorp Common Shares and result in dilution to the GX Stockholders that elect not to redeem. Furthermore, the outstanding NioCorp Assumed Warrants could have the effect of depressing the per share price for NioCorp Common Shares.

If GX Stockholders fail to comply with the redemption requirements specified herein, they will not be entitled to redeem their GX Common Stock for a pro rata portion of the funds held in the GX Trust Account.

In order to exercise your redemption rights, you must, (i) (A) hold GX Class A Shares, or (B) if you hold GX Class A Shares through GX Units, elect to separate your GX Units into the underlying GX Class A Shares and GX Public Warrants prior to exercising your redemption rights with respect to the GX Class A Shares and (ii) prior to 5:00 p.m. Eastern time on , 2023 (two business days before the GX Stockholder Meeting), (A) submit a written request to GX’s transfer agent that GX redeem your GX Class A Shares for cash and (B) deliver your stock to GX’s transfer agent physically or electronically through DTC. For more information about how GX Stockholders may exercise their redemption rights, see the question entitled “How do I exercise my redemption rights?”

If third parties bring claims against GX, the proceeds held in the Trust Account could be reduced and the per-share redemption amount received by stockholders may be less than $10.00 per share.

GX’s placing of funds in the Trust Account may not protect those funds from third-party claims against GX. Although GX has sought to have all vendors, service providers, prospective target businesses and other entities with which it does business execute agreements with GX waiving any right, title, interest or claim of any kind in or to any monies held in the Trust Account for the benefit of the GX Public Stockholders, such parties may not execute such agreements, or even if they execute such agreements they may not be prevented from bringing claims against the Trust Account, including, but not limited to, fraudulent inducement, breach of fiduciary responsibility or other similar claims, as well as claims challenging the enforceability of the waiver, in each case in order to gain advantage with respect to a claim against GX’s assets, including the funds held in the Trust Account. If any third-party refuses to execute an agreement waiving such claims to the monies held in

the Trust Account, GX’s management will perform an analysis of the alternatives available to it and will only enter into an agreement with a third party that has not executed a waiver if management believes that such third-party’s engagement would be significantly more beneficial to GX than any alternative. Marcum LLP, GX’s independent registered public accounting firm, and the underwriters of its IPO will not execute agreements waiving such claims to the monies held in the trust account.

Examples of possible instances where GX may engage a third party that refuses to execute a waiver include the engagement of a third-party consultant whose particular expertise or skills are believed by management to be significantly superior to those of other consultants that would agree to execute a waiver or in cases where management is unable to find a service provider willing to execute a waiver. In addition, there is no guarantee that such entities will agree to waive any claims they may have in the future as a result of, or arising out of, any negotiations, contracts or agreements with GX and will not seek recourse against the Trust Account for any reason. Upon redemption of the GX Class A Shares, if GX is unable to complete its initial business combination within the prescribed timeframe, or upon the exercise of a redemption right in connection with its initial business combination, GX will be required to provide for payment of claims of creditors that were not waived that may be brought against GX within the 10 years following redemption. Accordingly, the per-share redemption amount received by GX Public Stockholders could be less than the $10.00 per share initially held in the Trust Account, due to claims of such creditors. The Sponsor has agreed that it will be liable to GX if and to the extent any claims by a third-party for services rendered or products sold to GX, or a prospective target business with which GX has entered into a written letter of intent, confidentiality or similar agreement or business combination agreement, reduce the amount of funds in the Trust Account to below the lesser of (i) $10.00 per public share and (ii) the actual amount per public share held in the Trust Account as of the date of the liquidation of the Trust Account, if less than $10.00 per share due to reductions in the value of the trust assets, less taxes payable, provided that such liability will not apply to any claims by a third-party or prospective target business who executed a waiver of any and all rights to the monies held in the Trust Account (whether or not such waiver is enforceable) nor will it apply to any claims under GX’s indemnity of the underwriter of GX’s IPO against certain liabilities, including liabilities under the Securities Act. However, GX has not asked the Sponsor to reserve for such indemnification obligations, nor has GX independently verified whether the Sponsor has sufficient funds to satisfy its indemnity obligations and believes that the Sponsor’s only assets are securities of GX. Therefore, it is unlikely that GX’s Sponsor would be able to satisfy those obligations. None of GX’s officers or directors will indemnify GX for claims by third parties including, without limitation, claims by vendors and prospective target businesses.

The proceeds held in the Trust Account were, following GX’s IPO, invested only in U.S. government treasury obligations with a maturity of 185 days or less or in money market funds meeting certain conditions under Rule 2a-7 under the Investment Company Act, which invest only in direct U.S. government treasury obligations. While short-term U.S. government treasury obligations currently yield a positive rate of interest, they have briefly yielded negative interest rates in recent years. Central banks in Europe and Japan pursued interest rates below zero in recent years, and the Open Market Committee of the Federal Reserve has not ruled out the possibility that it may in the future adopt similar policies in the United States. In the event that GX is unable to complete its initial business combination or make certain amendments to the GX Existing Charter, GX Public Stockholders are entitled to receive their pro-rata share of the proceeds held in the Trust Account, plus any interest income not released to GX, net of taxes payable. Negative interest rates could impact the per-share redemption amount that may be received by GX Public Stockholders. However, to mitigate the risk of GX being deemed to be an unregistered investment company (including under the subjective test of Section 3(a)(1)(A) of the Investment Company Act) and thus subject to regulation under the Investment Company Act, as of the date of this joint proxy statement/prospectus, GX has instructed Continental Stock Transfer & Trust Company, the trustee with respect to the Trust Account, to liquidate the U.S. government treasury obligations or money market funds held in the Trust Account and thereafter to hold all funds in the Trust Account in cash until the earlier of the consummation of an initial business combination or the liquidation of GX. GX expects this process to be complete the week of February 6, 2023. Following such liquidation of the amounts in the Trust Account into cash, GX would likely receive minimal interest, if any, on the funds held in the Trust Account.

The U.S. federal income tax treatment of the redemption of GX Common Stock as a sale of such GX Common Stock depends on a shareholder’s specific facts.

The U.S. federal income tax treatment of a redemption of GX Common Stock to a particular shareholder electing to redeem GX Common Stock will depend on whether the redemption qualifies as a sale of such GX Common Stock under section 302(a) of the Code, which will depend largely on the total number of shares of GX Common Stock treated as held by the shareholder (including any stock constructively owned by the holder, including as a result of owning Private Placement Warrants or GX Public Warrants) relative to all of the stock of GX outstanding before and after the redemption. If such redemption is not treated as a sale of GX Common Stock for U.S. federal income tax purposes, the redemption will instead be treated as a corporate distribution. For more information about the U.S. federal income tax treatment of the redemption of GX Common Stock, see the section entitled “Material U.S. Federal Income Tax Considerations—Material U.S. Federal Income Tax Considerations With Respect to the Redemption and the Transactions—Treatment of U.S. Holders Exercising Redemption Rights With Respect to GX Class A Shares.”

The Excise Tax included in the Inflation Reduction Act of 2022 may impose a significant tax liability on GX after the Business Combination.

On August 16, 2022, President Biden signed into law the Inflation Reduction Act of 2022, which, among other changes, generally imposes a 1% excise tax on the fair market value of stock repurchased by certain publicly-traded domestic corporations beginning in 2023, subject to certain exceptions and adjustments (the “Excise Tax”). Because GX is a publicly-traded Delaware corporation, the Excise Tax may apply to any redemptions of GX Common Stock after December 31, 2022, including redemptions occurring in connection with the Transactions, unless an exception is available. Issuances of stock by GX in connection with the Transactions may reduce the amount of the Excise Tax resulting from such redemptions. After the Business Combination, GX will be an indirect subsidiary of NioCorp and any liability of GX for Excise Tax may reduce funds otherwise available for distribution or for use in the business of the Combined Company and may decrease the value of the Combined Company. The effect of the Excise Tax on GX and the Combined Company remains uncertain at this time due to the recent enactment of the Excise Tax and the potential impact of future regulations or other guidance relating to the Excise Tax.

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

The following unaudited pro forma condensed combined financial information is provided to aid you in your analysis of the financial aspects of the Transactions. This information should be read together with NioCorp’s and GX’s financial statements and related notes, the sections entitled “Selected Historical Consolidated Financial and Other Data,” “GX’s Management’s Discussion and Analysis of Financial Condition and Results of Operations” and the other financial information, in each case, contained elsewhere in or incorporated by reference into this joint proxy statement/prospectus.

Introduction

The following unaudited pro forma condensed combined financial information presents the combination of the financial information of NioCorp and GX as adjusted to give effect to the Transactions (including the Yorkville Financings). The following unaudited pro forma condensed combined financial information has been prepared in accordance with Article 11 of Regulation S-X, as amended by the final rule, Release No. 33-10786 “Amendments to Financial Disclosure about Acquired and Disposed Businesses.”

The unaudited pro forma condensed combined financial information was derived from and should be read in conjunction with the following historical financial statements and accompanying notes, which are included in or incorporated by reference into this joint proxy statement/prospectus:

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the (i) historical audited consolidated financial statements of NioCorp as of and for the fiscal year ended June 30, 2022 and (ii) historical unaudited condensed consolidated financial statements of NioCorp as of and for the three months ended September 30, 2022; and

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the (i) historical audited financial statements of GX as of and for the year ended December 31, 2021, (ii) historical unaudited condensed financial statements of GX as of and for the six months ended June 30, 2022 and 2021, and historical unaudited condensed financial statements of GX as of and for the three months ended September 30, 2022.

The Transactions will be accounted for as a recapitalization in accordance with GAAP. Under this method of accounting, GX will be treated as the “acquired” company for financial reporting purposes. This determination was primarily based on:

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predecessor NioCorp Shareholders’ voting interest in the Combined Company;

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the predecessor NioCorp Board having seven members that are retained into the Combined Company Board of nine members, thereby representing the majority of the members of the Combined Company Board;

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predecessor NioCorp management continuing to hold executive management roles for the post-combination company and being responsible for the day-to-day operations;

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the post-combination company assuming the NioCorp and Elk Creek Resources names;

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the pre-existing NioCorp headquarters will be maintained; and

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the intended strategy of the Combined Company being a continuation of predecessor NioCorp strategy, primarily the development of the Elk Creek Project.

Accordingly, the Transactions will be treated as a capital transaction of the issuance of NioCorp Common Shares for the net assets of GX, accompanied by a recapitalization. The net assets of GX will be stated at historical cost, with no goodwill or other intangible assets recorded. Operations prior to the Transactions will be those of NioCorp.

The unaudited pro forma condensed combined balance sheet as of September 30, 2022 combines the historical unaudited condensed consolidated balance sheet of NioCorp as of September 30, 2022 and the historical unaudited condensed balance sheet of GX as of September 30, 2022 on a pro forma basis as if the Transactions, summarized below, had been consummated on September 30, 2022.

The unaudited pro forma condensed combined statement of operations for the three months ended September 30, 2022 combines the historical unaudited interim condensed consolidated statement of operations of NioCorp for the three months ended September 30, 2022 and the historical unaudited interim condensed consolidated statement of operations of GX for the three month period ended September 30, 2022 on a pro forma basis as if the Transactions, summarized below, had been consummated on July 1, 2021, the beginning of the earliest period presented.

The unaudited pro forma condensed combined statement of operations for the year ended June 30, 2022 combines the historical consolidated statement of operations of NioCorp for the fiscal year ended June 30, 2022 and the aggregated historical condensed statement of operations of GX for the six month period from July 1, 2021 through December 31, 2021 and for the six month period from January 1, 2022 through June 30, 2022 on a pro forma basis as if the Transactions, summarized below, had been consummated on July 1, 2021, the beginning of the earliest period presented.

This unaudited pro forma condensed combined financial information is for informational purposes only and does not purport to indicate the results that would have been obtained had the Transactions actually been completed on the assumed date or for the periods presented, nor which may be realized or expected in the future. The pro forma adjustments are based on the information currently available and the assumptions and estimates underlying the pro forma adjustments are described in the accompanying notes. See “Notes to the Unaudited Pro Forma Condensed Combined Financial Information.” Actual results may differ materially from the assumptions within the accompanying unaudited pro forma condensed combined financial information. See “Cautionary Statement Regarding Forward-Looking Statements.”

Description of the Transactions

On September 25, 2022, NioCorp entered into the Business Combination Agreement with GX and Merger Sub. Pursuant to the Business Combination Agreement, among other things, the following transactions will occur. Merger Sub will merge with and into GX, with GX surviving the merger (the “First Merger”). Upon consummation of the First Merger, each GX Class A Share that is held by a GX Public Stockholder who has not elected to exercise their redemption rights shall be converted into a First Merger Class A Share. Immediately following the First Merger, NioCorp will exercise its unilateral option to purchase each First Merger Class A Share in exchange for 11.1829212 NioCorp Common Shares (the “Exchange”). Immediately following the Exchange, the First Merger Class A Shares then held by NioCorp will be contributed to Intermediate Holdco, a direct, wholly owned subsidiary of NioCorp, in exchange for additional shares of Intermediate Holdco (the “Contribution”). Immediately following the Contribution, ECRC will merge with and into the GX, with GX surviving the merger (the “Second Merger”) as a direct subsidiary of Intermediate Holdco.

Pursuant to the Business Combination Agreement, upon consummation of the First Merger, each Class B share in GX (other than certain shares that may be forfeited in accordance with the GX Support Agreement) will be converted into one share of Class B common stock in GX (the “First Merger Class B Shares”), as the surviving company in the First Merger. Upon consummation of the Second Merger, each of the First Merger Class B Shares will be converted into 11.1829212 Class B common shares of GX (each a “Second Merger Class B Share”), as the surviving company in the Second Merger, in a private placement. Each Second Merger Class B Share will be exchangeable into NioCorp Common Shares on a one-for-one basis, subject to certain equitable adjustments, in accordance with the terms of the Exchange Agreement as further discussed in Note 4 of the Notes to the Unaudited Pro Forma Condensed Combined Financial Information.

Each GX Warrant that is issued and outstanding immediately prior to the Exchange Time will be converted into one NioCorp Assumed Warrant pursuant to the GX Warrant Agreement. Each NioCorp Assumed Warrant will be exercisable solely for NioCorp Common Shares, and the number of NioCorp Common Shares subject to each NioCorp Assumed Warrant will be equal to the number of shares of GX Common Stock subject to the applicable GX Warrant multiplied by 11.1829212, with the applicable exercise price adjusted accordingly.

At the completion of the Second Merger, ownership of the NioCorp Common Shares outstanding held by GX Public Stockholders, the Sponsor, NioCorp Shareholders, and others, excluding Earnout Shares and NioCorp Assumed Warrants, will be as shown in the following table:

	No Redemption		Maximum Redemption
Ownership Group:	Shares	Ownership	Shares	Ownership
GXII Class A (public stockholders)	335,487,636	50.3%	2,348,413	0.7%
GXII Class B (founders)⁽¹⁾	47,650,427	7.1%	47,650,427	14.3%
Others⁽²⁾	4,769,574	0.7%	4,769,574	1.4%
NioCorp Shareholders	279,393,227	41.9%	279,393,227	83.6%
	667,300,864	100.0%	334,161,641	100.0%

(1) Excludes 34,230,920 Earnout Shares that are unvested and held by the GX Class B stockholders.

(2) Includes 3,343,693 NioCorp Common Shares issued to Cantor Fitzgerald, 788,455 NioCorp Common Shares issued under the Equity Facility, and 637,426 NioCorp Common Shares issued to BTIG.

On January 26, 2023, NioCorp entered into the Yorkville Convertible Debt Financing Agreement. The Yorkville Convertible Debt Financing Agreement is intended to be used, in part, to satisfy the fees and expenses incurred in connection with the Transactions, if required.

Pursuant to the Yorkville Convertible Debt Financing Agreement, Yorkville and any investor that exercises its contractual right previously granted by NioCorp to participate in the Yorkville Convertible Debt Financing (collectively with Yorkville, the “Investors”) will advance $15,360,000 to NioCorp, to take place in two closings (each a “Debenture Closing”), in consideration of the issuance by NioCorp to the Investors of $16,000,000 aggregate principal amount (the “Principal Amount”) of NioCorp Convertible Debentures.

Pursuant to the terms of the Yorkville Convertible Debt Financing Agreement, the Investors will advance (a) an initial total amount of $9,600,000 to NioCorp in consideration of the issuance by NioCorp to the Investors of $10,000,000 aggregate principal amount of NioCorp Convertible Debentures at the time of Closing (the “First Debenture Closing”), and (b) an additional total amount of $5,760,000 to NioCorp in consideration of the issuance by NioCorp to the Investors of $6,000,000 aggregate principal amount of NioCorp Convertible Debentures on a date to be determined at the election of NioCorp, but which may not be prior to the later to occur of (i) the date of filing of the registration statement registering the resale by the Investors of the NioCorp Common Shares issuable upon the conversion of the NioCorp Convertible Debentures and the exercise of the NioCorp Financing Warrants under the Securities Act (the “Convertible Debt Financing Registration Statement”) and (ii) the date of Closing.

Each NioCorp Convertible Debenture issued under the Yorkville Convertible Debt Financing will be an unsecured obligation of NioCorp, will have an 18-month term from the First Debenture Closing, which may be extended for one six-month period in certain circumstances at NioCorp’s option, and will incur a simple interest rate obligation of 5.0% per annum (which will increase to 15.0% per annum upon the occurrence of an event of default). The outstanding principal amount of, and accrued and unpaid interest, if any, and premium, if any, on, the NioCorp Convertible Debentures must be paid by NioCorp in cash when the same becomes due and payable under the terms of the NioCorp Convertible Debentures at stated maturity, upon redemption or otherwise.

Holders of the NioCorp Convertible Debentures will be entitled to convert each NioCorp Convertible Debenture, from time to time over their term, into a number of NioCorp Common Shares equal to the quotient of the principal amount and accrued and unpaid interest, if any, being converted divided by the Conversion Price. The “Conversion Price” means, as of any Conversion Date (as defined below) or other date of determination, the greater of (i) 90% of the average of the daily U.S. dollar VWAPs (as defined below) of the NioCorp Common Shares on the principal U.S. market for the NioCorp Common Shares (or, if the NioCorp Common Shares are not then listed on a principal U.S. market for the applicable period, on the exchange on which the NioCorp Common Shares are then listed as quoted on Bloomberg Financial Markets (or, if not available, a similar service provider of national recognized standing)) as reported by Bloomberg Financial Markets (or, if not available, a similar service provider of national recognized standing) during the five consecutive trading days immediately preceding the date on which the holder exercises its conversion right in accordance with the requirements of the Yorkville Convertible Debt Financing Agreement (the “Conversion Date”) or other date of determination, unless NioCorp consents to conversion at a lower price, and (ii) the five-day VWAP (expressed in U.S. dollars, based on the daily average CAD/USD exchange rate published by the Bank of Canada on the last day of the relevant calculation period) of the NioCorp Common Shares on the TSX (or on the principal U.S. market if the majority of the trading volume and value of the NioCorp Common Shares occurred on the Nasdaq Capital Market during the relevant period) for the five consecutive trading days immediately prior to the Conversion Date or other date of determination less the maximum applicable discount allowed by the TSX. Notwithstanding the foregoing, if at any time it shall be a condition to listing or continued listing of the NioCorp Common Shares on the Nasdaq or such other principal U.S. market for the NioCorp Common Shares that the Conversion Price be not less than a minimum price (the “Floor Price”), then NioCorp and the holders of the NioCorp Convertible Debentures will negotiate in good faith to amend the NioCorp Convertible Debentures to provide that the Conversion Price shall not be less than a Floor Price that satisfies such condition. Any Floor Price would be subject to adjustment to give effect to any stock dividend, stock split or recapitalization. No fractional NioCorp Common Shares will be issued upon conversion of the NioCorp Convertible Debentures. As to any fraction of a NioCorp Common Share to which the holder would otherwise be entitled upon such conversion, NioCorp will round down to the next whole NioCorp Common Share.

During any calendar month, each Investor (together with its affiliates) must limit conversions below the Fixed Conversion Price (as defined below) to the product of (a) the percentage of the total Principal Amount of the NioCorp Convertible Debentures represented by the NioCorp Convertible Debentures that were purchased by such Investor (together with its affiliates) and (b) the greater of (1) 20% of the monthly trading value of the NioCorp Common Shares on the principal U.S. market for the NioCorp Common Shares during the calendar month (or, if the NioCorp Common Shares have not been trading on the principal U.S. trading market for the NioCorp Common Shares for such period, 20% of the monthly trading value of the NioCorp Common Shares on the TSX) or (2) $2,250,000 in principal amount of the NioCorp Convertible Debentures. The “Fixed Conversion Price” means the quotient of (i) $10.00 divided by (ii) 11.1829212 (being the number of NioCorp Common Shares that will be exchanged for each share of GX pursuant to the Business Combination Agreement at the Closing), subject to adjustment to give effect to any stock dividend, stock split or recapitalization.

No Investor will have the right to convert a NioCorp Convertible Debenture into NioCorp Common Shares, or otherwise receive NioCorp Common Shares pursuant to the Yorkville Convertible Debt Financing (including with respect to the exercise of NioCorp Financing Warrants), in an amount that would result in such Investor (or its affiliates) beneficially owning (as determined in accordance with Section 13(d) of the Exchange Act and the rules promulgated thereunder) more than 4.99% of the NioCorp Common Shares outstanding immediately after giving effect to such conversion or receipt of shares (the “Beneficial Ownership Limitation”); provided that an Investor may waive the Beneficial Ownership Limitation as to itself upon not less than 65 days’ prior notice to NioCorp. Furthermore, no Investor will have the right to convert a NioCorp Convertible Debenture into NioCorp Common Shares, or otherwise receive NioCorp Common Shares pursuant to the Yorkville Convertible Debt Financing (including with respect to the exercise of NioCorp Financing Warrants), in an amount that would result in (a) a “change of control” under the rules and regulations of Nasdaq (the “Change of Control Limitation”), (b) the issuance of a number of NioCorp Common Shares that, together with the number of NioCorp Common Shares issued to any person pursuant to any prior conversion(s) of the NioCorp Convertible Debentures and any prior exercise(s) of the NioCorp Financing Warrants, would exceed 19.99% of the NioCorp Common Shares outstanding immediately prior to the effective date of the Yorkville Convertible Debt Financing Agreement (the “Issuance Limitation”) or (c) such Investor, together with any joint actors, beneficially owning or controlling (as determined in accordance with applicable securities laws in the Province of Ontario) more than 19.99% of the NioCorp Common Shares outstanding immediately after giving effect to such conversion or receipt of NioCorp Common Shares (the “TSX Cap”), except that the Change of Control Limitation, the Issuance Limitation and the TSX Cap shall not apply if the NioCorp Shareholders have approved issuances of NioCorp Common Shares in excess of the Change of Control Limitation, the Issuance Limitation or the TSX Cap in accordance with the requirements of the Nasdaq or TSX, respectively.

In conjunction with each Debenture Closing, NioCorp will issue to the Investors NioCorp Financing Warrants to purchase a number of NioCorp Common Shares as is equal to (N), determined pursuant to the following formula:

N = Quotient of the principal amount of NioCorp Convertible Debentures issued in such Debenture Closing divided by the “Exercise Price,” which is equal to the greater of:

(a)

the quotient of $10.00 divided by 11.1829212 (being the number of NioCorp Common Shares that will be exchanged for each share of GX pursuant to the Business Combination Agreement at Closing); or

(b)

the average of the daily VWAPs of the NioCorp Common Shares on the principal U.S. market for the NioCorp Common Shares (or on the exchange on which the NioCorp Common Shares are then listed as quoted by Bloomberg Financial Markets (or, if not available, a similar service provider of national recognized standing)) during regular trading hours as reported by Bloomberg Financial Markets during the five consecutive trading days ending on the trading day immediately prior to such Debenture Closing,

in each case, subject to any adjustment to give effect to any stock dividend, stock split or recapitalization.

The NioCorp Financing Warrants will be exercisable, in whole or in part, but not in increments of less than $50,000 aggregate Exercise Price (unless the remaining aggregate Exercise Price is less than $50,000), beginning on the earlier of (a) six months following the issuance of the applicable NioCorp Financing Warrants or (b) the effective date of the initial Convertible Debt Financing Registration Statement (such earlier date, the “Exercise Date”) and may be exercised at any time prior to their expiration. Holders of the NioCorp Financing Warrants may exercise their NioCorp Financing Warrants, at their election, by paying the Exercise Price in cash or on a cashless exercise basis. On each of the first 12 monthly anniversaries of the Exercise Date, 1/12th of the NioCorp Financing Warrants will expire. No fractional NioCorp Common Shares will be issued upon exercise of the NioCorp Financing Warrants. As to any fraction of a NioCorp Common Share that the holder would otherwise be entitled to purchase upon such exercise, NioCorp will round down to the next whole NioCorp Common Share.

As a result of the Transactions, GX will become a subsidiary of NioCorp, each GX Public Stockholder who does not elect to exercise their redemption rights will ultimately be issued NioCorp Common Shares and each GX Warrant will be converted into a NioCorp Assumed Warrant.

The value of the aggregate equity value of the outstanding GX Class A Shares and GX Class B Shares before the Transactions and prior to redemptions was determined to be $343.5 million, based on the pro rata redemption amount per share as of September 30, 2022 of approximately $10.00 per share, as shown in the following table:

Share Class	Shares Outstanding	Value per Share	Total Value
Class A	30,000,000	$10.00	$300,000,000
Class B	4,350,000	10.00	43,500,000
Total	34,350,000	$10.00	$343,500,000

The unaudited pro forma condensed combined financial information contained herein assumes that NioCorp Shareholders and the GX Stockholders approve the NioCorp Proposals and the GX Proposals necessary to effect the Transactions, as applicable.

The unaudited pro forma condensed combined financial information has been prepared using the assumptions below with respect to the potential redemption for cash of GX Class A Shares:

●

Assuming No Redemptions: This presentation assumes that no GX Public Stockholders exercise redemption rights with respect to their GX Class A Shares for a pro rata share of the funds in the Trust Account. Under the assumption of no redemptions, each of the 30.0 million of GX Class A Shares will be exchanged for 11.1829212 NioCorp Common Shares, resulting in the issuance of 335,487,636 NioCorp Common Shares.

●

Assuming Maximum Redemptions: This presentation assumes that GX Public Stockholders holding 29.790 million GX Class A Shares will exercise their redemption rights for their pro rata share (approximately $10.00 per share as of September 30, 2022) of the funds in the Trust Account. Under this assumption, each of 210,000 of GX Class A Shares will be exchanged for 11.1829212 NioCorp Common Shares, resulting in the issuance of 2,348,413 NioCorp Common Shares. This exercise rate is estimated to be the maximum amount of redemptions that could occur and still permit the Combined Company to satisfy the Closing condition that the Combined Company and its subsidiaries (including GX, as the surviving company of the Second Merger) will have net tangible assets of at least $5,000,001 immediately upon the consummation of the Transactions, after giving effect to any redemptions by GX Public Stockholders and after payment of underwriters’ fees or commissions.

Potentially dilutive instruments and Class B equity are discussed below in Note 3 - Loss Per Share and Note 4 – Second Merger Class B Shares, respectively, of the Notes to the Unaudited Pro Forma Condensed Combined Financial Information.

The following unaudited pro forma condensed combined balance sheet as of September 30, 2022 and the unaudited pro forma condensed combined statements of operations for the three months ended September 30, 2022 and for the year ended June 30, 2022, are based on the historical financial statements of NioCorp and GX. The unaudited pro forma adjustments are based on information currently available, and assumptions and estimates underlying the unaudited pro forma adjustments are described in the accompanying Notes to the Unaudited Pro Forma Condensed Combined Financial Information. If the actual facts are different than these assumptions, then the amounts and shares outstanding in the unaudited pro forma condensed combined financial information that follows will be different, and those changes could be material.

UNAUDITED PRO FORMA CONDENSED COMBINED BALANCE SHEET
AS OF SEPTEMBER 30, 2022
(Dollars in Thousands)

								Assuming no redemptions						Assuming maximum redemptions
	NioCorp Developments Ltd.			GX Acquisition Corp. II			Notes	Pro forma Adjustments			Pro forma Combined			Pro forma Adjustments			Pro forma Combined
	(Historical)			(Historical)			Notes
ASSETS
Current
Cash	$	3,192		$	13		A,B,C,D,E,H	$	299,690		$	302,895		$	884		$	4,089
Prepaid expenses and other		189			465				-			654			-			654
Total current assets		3,381			478				299,690			303,549			884			4,743
Non-current
Deferred transaction costs		2,809			-		A		(2,809	)		-			(2,809	)		-
Deferred equity transaction costs		-			-		H		2,150			2,150			2,150			2,150
Deposits		35			-				-			35			-			35
Investment in equity securities		10			-				-			10			-			10
Right-of-use assets		76			-				-			76			-			76
Land and buildings, net		850			-				-			850			-			850
Mineral properties		16,085			-				-			16,085			-			16,085
Marketable securities held in Trust Account		-			300,912		D,E		(300,912	)	-				(300,912	)	-
Total assets	$	23,246		$	301,390			$	(1,881	)	$	322,755		$	(300,687	)	$	23,949
LIABILITIES
Current
Accounts payable and accrued liabilities	$	3,670		$	4,554		A,B,H	$	(6,164	)	$	2,060		$	(6,164	)	$	2,060
Related party loan		2,000			-				-			2,000			-			2,000
Convertible Debt, current portion		755			-				-			755			-			755
Operating lease liability		86			-				-			86			-			86
Total current liabilities		6,511			4,554				(6,164	)		4,901			(6,164	)		4,901
Non-current
Convertible debt		-			-		H		9,660			9,660			9,660			9,660
Warrant liabilities		-			1,567		I		(1,000)			567			(1,000	)		567
Contingent share obligation		-			-		G		3,125			3,125			3,125			3,125
Deferred underwriting fee payable		-			10,500		C		(10,500	)		-			(10,500	)		-
Total liabilities		6,511			16,621				(4,879	)		18,253			(4,879	)		18,253
Commitments and Contingencies
Class A common stock subject to possible redemption at redemption value		-			300,882		D,E		(300,882	)		-			(300,882	)		-
SHAREHOLDERS’ EQUITY
Common stock		130,684			-		A,B,C,D,E,F,G,H,I		245,103			375,787			(53,703	)		76,981
Common stock - Class B		-			1		D,E		(1	)		-			(1	)		-
Accumulated deficit		(112,951	)		(16,114	)	A,B,C,F		16,038			(113,027	)		16,038			(113,027	)
Accumulated other comprehensive loss		(998	)		-				-			(998	)		-			(998	)
Total shareholder equity attributable to NioCorp shareholders		16,735			(16,113	)			261,140			261,762			(37,666	)		(37,044	)
Noncontrolling interests in consolidated subsidiaries		-			-		D,E		42,740			42,740			42,740			42,740
Total shareholder equity		16,735			(16,113	)			303,880			304,502			5,074			5,696
Total liabilities and equity	$	23,246		$	301,390			$	(1,881	)	$	322,755		$	(3

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