SWN Southwestern Energy

NOTICE OF SPECIAL MEETING OF SHAREHOLDERS

OF

SOUTHWESTERN ENERGY COMPANY

TO BE HELD ON AUGUST 27, 2021

You are cordially invited to attend a special meeting of shareholders (the “Special Meeting”) of Southwestern Energy Company (“SWN”).

At the meeting, SWN plans to ask you to:

SWN’s Board of Directors unanimously recommends that you vote “FOR” the Stock Issuance Proposal, “FOR” the Authorized Share Increase Proposal and “FOR” the Adjournment Proposal.

The above proposals are more fully described in the accompanying proxy statement, which also includes, as Annex B, a copy of the Merger Agreement. We urge you to read carefully the accompanying proxy statement in its entirety, including the Annexes.

Please see the instructions in the “Questions and Answers About the Proposals for the Special Meeting” section in the accompanying proxy statement, which provides additional information on how to participate in the Special Meeting.

We urge each shareholder to promptly sign and return the enclosed proxy card or to use phone or Internet voting.

On behalf of the Board of Directors,

Chris Lacy

Vice President, General Counsel & Secretary

July 20, 2021

Important Notice Regarding the Availability of Proxy Materials for the Special Meeting of Shareholders To Be Held on August 27, 2021

The proxy statement for the special meeting of shareholders of Southwestern Energy Company is attached. The proxy statement for the special meeting of shareholders of Southwestern Energy Company and a form of proxy card are available free of charge at www.proxyvote.com.

SUMMARY TERM SHEET

This summary term sheet, together with the section entitled “Summary of the Proxy Statement,” summarizes certain information contained in this proxy statement, but does not contain all of the information that is important to you. You should read carefully this entire proxy statement, including the attached Annexes, for a more complete understanding of the matters to be considered at the Special Meeting.

For definitions used commonly throughout this proxy statement, including this summary term sheet, please see the section entitled “Frequently Used Terms.”

FREQUENTLY USED TERMS

Throughout this proxy statement, references to “Southwestern Energy,” “Southwestern” or “SWN” refer to Southwestern Energy Company, a Delaware corporation, and not its consolidated subsidiaries, and references to “we,” “us,” “our” and the “Company” refer collectively to Southwestern and its consolidated subsidiaries.

In addition, throughout this proxy statement, except as otherwise indicated:

“AFE” means any authorization for expenditure or other capital proposal to conduct operations relating to the Oil & Gas Assets.

“Barrel” or “Bbl” means one barrel of petroleum products that equals 42 U.S. gallons.

“Bcf” means billion cubic feet.

“Bcfe” means billion cubic feet of natural gas equivalent, with one barrel of NGLs and crude oil being equivalent to six Mcf of natural gas.

“Board” or “Board of Directors” means the board of directors of SWN.

“British Thermal Unit” means a unit of energy needed to raise the temperature of one pound of water by one degree Fahrenheit.

“Business Day” means any day other than a Saturday, Sunday or other day on which commercial banks are authorized or required by applicable law to be closed in Houston, Texas.

“Cash Consideration” means $400 million in cash, as adjusted pursuant to the Merger Agreement.

“Class A Common Units” means the Class A Common Units of Indigo.

“Class B Common Units” means the Class B Common Units of Indigo.

“Common Stock” means the shares of SWN’s common stock, par value $0.01 per share.

“Company,” “we,” “us” or “our” means Southwestern Energy Company, a Delaware corporation, and its subsidiaries.

“Computershare” means Computershare Limited, SWN’s transfer agent.

“DGCL” means the General Corporation Law of the State of Delaware, as amended.

“Exchange Act” means the Securities Exchange Act of 1934, as amended.

“Execution Date” means June 1, 2021.

“GAAP” means accounting principles generally accepted in the United States as in effect from time to time.

“Goldman Sachs” means Goldman Sachs & Co. LLC, financial advisor to SWN with respect to the Merger.

“HSR Act” means the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended.

“Hydrocarbons” means oil, gas, minerals, and other gaseous and liquid hydrocarbons, or any combination of the foregoing, produced from and attributable to the Oil & Gas Assets (as defined in the Merger Agreement).

“Incentive Unit” means an Incentive Unit of Indigo.

“Indigo” means Indigo Natural Resources LLC, a Delaware limited liability company.

“Indigo Fundamental Representations and Warranties” means those representations and warranties of Indigo set forth in Section 7.1, Section 7.2(a), Section 7.2(b) (solely with respect to the Indigo LLC Agreement), Section 7.3, Section 7.4(a), Section 7.4(b), Section 7.4(c), Section 7.5(a), and Section 7.7 of the Merger Agreement.

“Indigo Group” means, collectively, Indigo and the subsidiaries of Indigo, and following the closing, each of their successors and permitted assigns.

“Indigo Group Member” means any member of the Indigo Group.

“Indigo Holder” means any holder of an Indigo Unit.

“Indigo LLC Agreement” means the Amended and Restated Limited Liability Company Agreement of Indigo, dated as of February 6, 2018, as in effect on the date of the Merger Agreement.

“Indigo Minerals” means Indigo Minerals LLC, a Delaware limited liability company.

“Indigo Notes” means Indigo’s 5.375% Senior Notes due 2029.

“Indigo Parties” means Indigo and the Unitholder Representative.

“Indigo Revolving Credit Facility” means that certain Third Amended and Restated Credit Agreement, dated as of February 6, 2018, by and among Indigo, as borrower, Wells Fargo Bank, N.A., in its capacity as administrative agent, and the financial institutions party thereto as lenders from time to time (as amended, supplemented or otherwise modified from time to time).

“Indigo Units” means the Class A Common Units, the Class B Common Units, the Preferred Units and the Incentive Units.

“MBbls” means one thousand Barrels.

“Mcf” means one thousand cubic feet.

“Merger” means the merger of Merger Sub with and into Indigo, with Indigo continuing as the surviving company and becoming a wholly owned subsidiary of SWN.

“Merger Agreement” means that certain Agreement and Plan of Merger, dated as of June 1, 2021, as it may be amended from time to time, by and among the SWN Parties and the Indigo Parties, a copy of which is included as Annex B.

“Merger Sub” means Ikon Acquisition Company, LLC, a Delaware limited liability company and wholly owned subsidiary of SWN.

“Montage” means Montage Resources Corporation, a Delaware corporation.

“Montage Merger” means the merger of Montage with and into SWN, with SWN continuing as the surviving company.

“Morrow” means Morrow Sodali LLC, SWN’s proxy solicitor.

“NGL” means natural gas liquids. Natural gas liquids result from natural gas processing and crude oil refining and are used as petrochemical feedstocks, heating fuels and gasoline additives, among other applications.

“NYMEX” means the New York Mercantile Exchange.

“NYSE” means the New York Stock Exchange.

“NYSE Listed Company Manual” means the NYSE Listed Company Manual, as amended from time to time, and any successor rule or regulation.

“NYSE Listing Rule 312.03” means Rule 312.03 of the NYSE Listed Company Manual.

“Preferred Unit” means a Preferred Unit of Indigo.

“PWC” means PricewaterhouseCoopers LLP, independent registered public accounting firm to SWN.

“SEC” means the Securities and Exchange Commission.

“Securities Act” means the Securities Act of 1933, as amended.

“Skadden” means Skadden, Arps, Slate, Meagher & Flom LLP, counsel to SWN with respect to the Merger.

“Special Meeting” means the special meeting of SWN’s shareholders that is the subject of this proxy statement.

“Stock Consideration” means 339,270,568 shares of Common Stock, as adjusted pursuant to the Merger Agreement.

“SWN” means Southwestern Energy Company, a Delaware corporation.

“SWN Fundamental Representations and Warranties” means those representations and warranties of SWN set forth in Section 8.1, Section 8.2, Section 8.3, Section 8.4(a), Section 8.8, Section 8.11 and Section 8.13 of the Merger Agreement.

“SWN Group” means, collectively, SWN and its subsidiaries.

“SWN Parties” means SWN and Merger Sub.

“Title Threshold Amount” means $150,000.

“Unitholder Representative” means Ibis Unitholder Representative LLC, a Delaware limited liability company, solely in its capacity as the representative of the Indigo Holders under the Merger Agreement.

“VIF” means a voting instruction form.

DEFINITIVE PROXY STATEMENT, DATED JULY 20, 2021

On behalf of the Board, SWN is soliciting proxies to be voted at the Special Meeting to be held on August 27, 2021 at 9 a.m. Central Time, for the purposes set forth herein. Giving SWN your proxy means you authorize SWN to vote your shares at the Special Meeting in the manner you direct or if you provide no direction, as described herein.

This proxy statement and the form of proxy were first mailed on or about July 22, 2021 to all shareholders of SWN as of July 12, 2021, the record date for the Special Meeting. This proxy statement contains important information about the items you will vote on at the Special Meeting and about the voting process.

QUESTIONS AND ANSWERS ABOUT THE PROPOSALS FOR THE SPECIAL MEETING

SWN has entered into the Merger Agreement providing for the acquisition of all of the Indigo Units, for aggregate consideration consisting of $400,000,000 in cash and 339,270,568 shares of Common Stock, in each case subject to adjustment as provided in the Merger Agreement.

Subject to the terms of the Merger Agreement (including the adjustment of the final consideration thereunder), the aggregate consideration to be paid in connection with the Merger is expected to be approximately $2,000,000,000 in cash and Common Stock. A copy of the Merger Agreement is attached to this proxy statement as Annex B.

This proxy statement and its Annexes contain important information about the proposed Merger and the other matters to be acted upon at the Special Meeting. You should read this proxy statement and its Annexes carefully and in their entirety.

Your vote is important. You are encouraged to submit your proxy as soon as possible after carefully reviewing this proxy statement and its Annexes.

Assuming a quorum is present, approval of the Stock Issuance Proposal requires the affirmative vote of the holders of a majority of the shares of Common Stock present in person or represented by proxy at the Special Meeting and entitled to vote thereat. Accordingly, with respect to a holder of shares of Common Stock who is present in person or represented by proxy at the Special Meeting, such shareholder’s abstention from voting or the failure of a holder of shares of Common Stock to vote will have the same effect as a vote “AGAINST” the Stock Issuance Proposal. The failure of a holder of shares of Common Stock who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to the bank, broker or other nominee also will have the same effect as a vote “AGAINST” the Stock Issuance Proposal if such bank, broker or other nominee exercises its authority to vote in its discretion on the Authorized Share Increase Proposal. Additionally, if a holder of shares of Common Stock instructs its bank, broker or other nominee regarding the Authorized Share Increase Proposal or the Adjournment Proposal but not the Stock Issuance Proposal, such broker non-vote will have the same effect as voting “AGAINST” the Stock Issuance Proposal.

Approval of the Authorized Share Increase Proposal requires the affirmative vote of the holders of a majority of the outstanding shares of Common Stock entitled to vote on the proposal. Accordingly, an abstention from a holder of shares of Common Stock will have the same effect as a vote “AGAINST” the Authorized Share Increase Proposal. The failure to instruct your bank, broker or other nominee how you wish to vote your shares with respect to the Authorized Share Increase Proposal will permit such bank, broker or other nominee to exercise its authority to vote in its discretion on the Authorized Share Increase Proposal.

Approval of the Adjournment Proposal requires the affirmative vote of the holders of a majority of the shares of Common Stock present in person or represented by proxy at the Special Meeting and entitled to vote thereat. Accordingly, with respect to a holder of shares of Common Stock who is present in person or represented by proxy at the Special Meeting, such shareholder’s abstention from voting or the failure of a holder of shares of Common Stock to vote will have the same effect as a vote “AGAINST” the Adjournment Proposal. The failure of a holder of shares of Common Stock who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to the bank, broker or other nominee also will have the same effect as a vote “AGAINST” the Adjournment Proposal if such bank, broker or other nominee exercises its authority to vote in its discretion on the Authorized Share Increase Proposal. Additionally, if a holder of shares of Common Stock instructs its bank, broker or other nominee regarding the Stock Issuance Proposal or the Authorized Share Increase Proposal, but not the Adjournment Proposal, such broker non-vote will have the same effect as voting “AGAINST” the Adjournment Proposal. Unless there is a quorum, the presiding officer of the Special Meeting may also adjourn the Special Meeting.

Street Name Holders. If you hold your shares in an account at a bank or broker, then you are the beneficial owner of shares held in “street name.” The proxy materials were forwarded to you by your bank or broker, who is considered the shareholder of record for purposes of voting at the Special Meeting. As a beneficial owner, you have the right to direct your bank or broker on how to vote the shares held in your account.

If you are the record holder of your shares, you may vote your shares (i) using your proxy card (see the next question), (ii) via the Internet, (iii) by phone, or (iv) in person at the Special Meeting by proxy. If your shares are held by your broker in “street name,” your broker is required to provide you with instructions for voting your shares.

Internet Access: Record holders with Internet access may submit proxies by following the “Vote by Internet” instructions on their proxy cards. Shareholders who hold shares beneficially in “street name” may vote by

accessing the website specified on the voting instruction cards provided by their brokers, trustee or nominees. Please check the voting instruction card for Internet voting availability.

By Phone: Record holders may submit proxies by following the “Vote by Phone” instructions on their proxy cards. Shareholders who hold shares beneficially in “street name” may vote by phone by calling the number specified on the voting instruction card provided by their brokers, trustee or nominees. Please check the voting instruction card for telephonic voting availability.

Step 2: Sign and date your proxy card. IF YOU DO NOT SIGN AND DATE YOUR PROXY CARD, YOUR VOTES WILL NOT BE COUNTED. EACH PROPERLY EXECUTED PROXY WILL BE VOTED IN THE MANNER DIRECTED. IF NO DIRECTION IS MADE, EACH SUCH PROXY WILL BE VOTED IN ACCORDANCE WITH THE BOARD’S RECOMMENDATIONS AS SET FORTH IN THIS PROXY STATEMENT.

Step 3: Mail your proxy card in the pre-addressed, postage-paid envelope.

Your bank, broker or other holder of record (or designee thereof) will vote your shares in accordance with the instructions on your returned VIF. You may instruct the holder of record to vote your shares by completing the VIF as outlined in the instructions on the form and signing, dating and returning the VIF in the prepaid envelope provided. You may also submit your vote by phone or on the Internet if those options are made available to you by your bank, broker or other holder of record. Although most banks, brokers and other nominees offer these voting alternatives, availability and specific procedures vary. Please instruct your bank, broker or other holder of record how to vote your shares so that your vote can be counted. Please review your VIF for the date by which your instructions must be received in order for your shares to be voted.

The effect of not instructing your bank, broker or other nominee how you wish to vote your shares with respect to the Authorized Share Increase Proposal will permit such bank, broker or other nominee to exercise its authority to vote in its discretion on the Authorized Share Increase Proposal. Accordingly, the effect of not instructing your bank, broker or other nominee how you wish to vote your shares will be the same as a vote “AGAINST” the Stock Issuance Proposal and the Adjournment Proposal if your bank, broker or other nominee exercises its authority to vote in its discretion on the

Authorized Share Increase Proposal. If you instruct your bank, broker or other nominee on how you wish to vote your shares on:

You are encouraged to have all accounts registered in the same name and address whenever possible. You can do this by contacting Computershare at P.O. Box 505000, Louisville, Kentucky 40233, at its toll-free number (1-800-446-2617) or on its website at http://www.computershare.com/investor. If you receive more than one VIF, please contact the bank, broker or other holder of record holding your shares to determine whether you can consolidate your accounts.

If a shareholder of record residing at a household to which SWN sent only one copy of this proxy statement wishes to receive an additional copy for the Special Meeting, he or she may contact SWN’s Secretary. See “How do I contact SWN’s Secretary?” below. SWN will promptly deliver, upon written or oral request, a separate copy of this proxy statement to a shareholder at a shared address to which a single copy of the documents was delivered.

If a shareholder of record residing at a household to which SWN sent only one copy of this proxy statement wishes to receive separate documents in the future, he or she may discontinue householding by contacting Computershare at P.O. Box 505000, Louisville, Kentucky 40233, at its toll-free number (1-800-446-2617) or on its website at http://www.computershare.com/investor.

If you are an eligible shareholder of record receiving multiple copies of this proxy statement, you can request householding in the future by contacting SWN’s Secretary. See “How do I contact SWN’s Secretary?” below. If you own your shares through a bank, broker or other holder of record, you can request householding by contacting the applicable holder of record.

Southwestern Energy Company

Attention: Secretary

10000 Energy Drive

Spring, Texas 77389

(832) 796-7877

Southwestern Energy Company

Attention: Secretary

10000 Energy Drive

Spring, Texas 77389

(832) 796-7877

You may also contact SWN’s proxy solicitor at:

Morrow Sodali LLC

509 Madison Avenue, Suite 1206

New York, NY 10022

Individuals, banks and brokers, please call toll-free: (800) 662-5200

To obtain timely delivery, SWN shareholders must request the materials no later than five Business Days prior to the Special Meeting.

You may also obtain additional information about SWN from documents filed with the SEC by following the instructions in the section entitled “Where You Can Find More Information; Incorporation of Certain Documents by Reference.”

The SEC has an informational website that provides shareholders with general information about how to cast their vote and why voting should be an important consideration for shareholders. You may access that information at www.sec.gov/spotlight/proxymatters.shtml or at www.investor.gov.

SUMMARY OF THE PROXY STATEMENT

This summary highlights selected information contained in this proxy statement and does not contain all of the information that may be important to you. You should read carefully this entire proxy statement, including the Annexes and accompanying financial statements of Indigo, to fully understand the proposed Merger before voting on the proposals to be considered at the Special Meeting. Please see the section entitled “Where You Can Find More Information; Incorporation of Certain Documents by Reference” beginning on page 155 of this proxy statement.

The Parties to the Merger

The Company

We are an independent energy company engaged in exploration, development and production activities, including the related marketing of natural gas, oil and natural gas liquids produced in our operations. We are a holding company whose assets consist of direct and indirect ownership interests in, and whose business is conducted substantially through, its subsidiaries. Currently we operate exclusively in the United States. Our Common Stock is listed and traded on the NYSE under the ticker symbol “SWN.”

Southwestern, which is incorporated in Delaware, has its executive offices located at 10000 Energy Drive, Spring, Texas 77389, and can be reached by phone at 832-796-1000. The Company also maintains offices in Tunkhannock, Pennsylvania, Morgantown, West Virginia, and Zanesville, Ohio.

Our Business Strategy

We aim to deliver sustainable and industry-leading returns through excellence in exploration and production and marketing performance from our extensive resource base and targeted expansion of our activities and assets along the hydrocarbon value chain. Our Company’s formula embodies our corporate philosophy and guides how we operate our business:

Our formula, “The Right People doing the Right Things, wisely investing the cash flow from our underlying Assets will create Value+,” also guides our business strategy. We always strive to attract and retain strong talent, to work safely and act ethically with unwavering vigilance for the environment and the communities in which we operate, and to creatively apply technical skills, which we believe will grow long-term value for our shareholders. The arrow in our formula is not a straight line: we acknowledge that factors may adversely affect quarter-by-quarter results, but the path over time points to value creation.

In applying these core principles, we concentrate on:

The bulk of our operations, which we refer to as “Exploration and Production,” are focused on the finding and development of natural gas, oil and NGL reserves. We are also focused on creating and capturing additional value through our marketing business, which we refer to as “Marketing.”

Indigo

Indigo is one of the largest private US natural gas producers, with core dry gas assets across the stacked pay Haynesville and Bossier zones in northern Louisiana. Its high-margin assets are located in close proximity to the Gulf Coast LNG corridor.

For more information about Indigo, please see the sections entitled “Information About Indigo” and “Indigo’s Management’s Discussion and Analysis of Financial Condition and Results of Operations.”

The Merger Agreement and Related Agreements

On June 1, 2021, the SWN Parties entered into the Merger Agreement with the Indigo Parties, pursuant to which SWN will acquire all of the Indigo Units in exchange for the consideration described below. Upon the terms and subject to the conditions of the Merger Agreement, Merger Sub will merge with and into Indigo, with Indigo continuing as the surviving company and a wholly owned subsidiary of SWN.

Under the terms and conditions of the Merger Agreement, the aggregate consideration to be paid to the Indigo Holders in the Merger will consist of the Cash Consideration and the Stock Consideration, which shares comprising the Stock Consideration had an aggregate market value of approximately $1.6 billion based on the volume weighted average sales price as traded on the NYSE of such shares calculated for the 30 trading day period ending on May 28, 2021.

In connection with the closing of the Merger, SWN will enter into a registration rights agreement (the “Registration Rights Agreement”) with certain holders of Indigo Units (the “RRA Holders”) that will receive a portion of the Stock Consideration to be issued at the closing of the Merger. Pursuant to the Registration Rights Agreement, among other things, SWN (a) is required to file with the SEC a registration statement on Form S-3 registering for resale the shares of Common Stock received by the RRA Holders as part of the Merger (the “Shelf Registration Statement”) and (b) will grant certain RRA Holders certain demand and piggyback registration rights.

In connection with entering into the Registration Rights Agreement, SWN will also enter into lockup agreements with certain RRA Holders who, in the aggregate, own approximately 95% of the outstanding interests in Indigo (the “Lockup Agreements”), pursuant to which, among other things, each such RRA Holder will agree to sell only up to a certain specified portion of the Stock Consideration received in the Merger as follows: the RRA Holders subject to the Lockup Agreements may (i) not sell any Registrable Securities (as defined in the Registration Rights Agreement) on or before the date that is 30 days following the closing and (ii) sell up to an aggregate of 25% of the Registrable Securities beginning on the 31st day after closing pursuant to the Shelf Registration Statement, including pursuant to up to (a) one shelf underwritten offering on or before the date that is six months following closing and (b) two shelf underwritten offerings on or after the date that is six months following the closing.

The foregoing descriptions of the Merger Agreement, the Registration Rights Agreement and the Lockup Agreements do not purport to be complete and are subject to, and qualified in their entirety by, the full text thereof. The Merger Agreement is included as Annex B of this proxy statement, and the form of Registration Rights Agreement and the form of Lockup Agreement are included in Annex C of this proxy statement. Shareholders and other interested parties are urged to read these agreements in their entirety prior to voting on the proposals presented at the Special Meeting.

Proposal No. 1: The Stock Issuance Proposal

Pursuant to the Merger Agreement, SWN’s shareholders will be asked to approve, for purposes of complying with Rule 312.03, the issuance of shares of Common Stock pursuant to the Merger Agreement. For more information about the issuance contemplated by the Merger Agreement, please see the section entitled “Proposal No. 1—Approval of the Issuance of Common Stock in Connection with the Merger.” The Merger is conditioned on, among other things, the approval of the Stock Issuance Proposal at the Special Meeting.

Proposal No. 2: The Authorized Share Increase Proposal

SWN’s shareholders will be asked to vote on a proposal to approve the Charter Amendment and the Authorized Share Increase Proposal for purposes of authorizing the number of shares of Common Stock SWN may issue from time to time. The Merger is not conditioned on the approval of the Authorized Share Increase Proposal. For more information about the Authorized Share Increase Proposal, please see the section entitled “Proposal No. 2—The Authorized Share Increase Proposal.”

Proposal No. 3: The Adjournment Proposal

SWN’s shareholders will be asked to vote on a proposal to approve one or more adjournments of the Special Meeting, if necessary or appropriate, to permit solicitation of additional votes if there are insufficient votes to approve the Stock Issuance Proposal. Please see the section entitled “Proposal No. 3—The Adjournment Proposal” for more information.

Date, Time and Place of Special Meeting

The Special Meeting will be held at Southwestern Energy Company Headquarters, 10000 Energy Drive, Spring, Texas 77389, on August 27, 2021 at 9 a.m. Central Time, or at such other date, time and place to which such meeting may be adjourned or postponed, to consider and vote upon the proposals.

Voting Power; Record Date

Only holders of shares of Common Stock of record at the close of business on July 12, 2021, the record date for the Special Meeting, will be entitled to vote at the Special Meeting. You are entitled to one vote for each share of Common Stock that you owned at the close of business on the record date. If your shares are held in “street name” or are in a margin or similar account, you should contact your bank, broker or other holder of record to ensure that votes related to the shares you beneficially own are properly counted. On the record date, there were 677,021,254 shares of Common Stock outstanding and entitled to vote.

Accounting Treatment

The Merger will be accounted for using the acquisition method of accounting for business combinations. The allocation of the preliminary estimated merger consideration is based upon management’s estimates of and assumptions related to the fair value of assets to be acquired and liabilities to be assumed. SWN expects to finalize its allocation of the purchase consideration as soon as practicable after completion of the Merger, but SWN is not required to finalize such allocation for one year from the closing date of the Merger. For U.S. federal income tax purposes, the Merger will be treated as an asset purchase (such that the tax basis in the Indigo assets will generally reflect the allocated fair value at closing) and direct liability assumption.

Appraisal Rights

No dissenters’ or appraisal rights will be available to the holders of Common Stock with respect to the Merger or the other transactions contemplated by the Merger Agreement.

Proxy Solicitation

SWN is soliciting proxies on behalf of the Board. This proxy solicitation is being made by mail, but also may be made by phone or in person. SWN has also engaged Morrow to assist in the solicitation of proxies. SWN and its directors, officers and employees may also solicit proxies in person. SWN will ask banks, brokers and other institutions, nominees and fiduciaries to forward the proxy materials to their principals and to obtain their authority to execute proxies and voting instructions.

SWN will bear the entire cost of the proxy solicitation, including the preparation, assembly, printing, mailing and distribution of the proxy materials. SWN estimates it will pay Morrow a fee of approximately $25,000, plus reimburse Morrow for its reasonable out-of-pocket expenses. SWN will reimburse brokerage firms and other custodians for their reasonable out-of-pocket expenses for forwarding the proxy materials to SWN’s shareholders. Directors, officers and employees of SWN who solicit proxies will not be paid any additional compensation for soliciting proxies.

If a shareholder grants a proxy, it may still vote its shares in person if it revokes its proxy before the Special Meeting. A shareholder may also change its vote by submitting a later-dated proxy, as described in the section entitled “Questions and Answers About the Proposals for Shareholders Special Meeting—May I change my vote?”

Reasons for the Approval of the Stock Issuance in Connection with the Merger

The Board considered the following positive factors, although not weighted or in any order of significance, in approving the Merger and the issuance of the Stock Consideration in connection with the Merger:

For more information about SWN’s decision-making process, please see the section entitled “Proposal No. 1—Approval of the Issuance of Common Stock in Connection with the Merger—Background of the Merger—The Board’s Reasons for the Approval of the Merger and the Stock Issuance.”

Conditions to Closing of the Merger

Conditions to Each Party’s Obligations

The respective obligations of the SWN Parties and the Indigo Parties to consummate and effect the Merger and the other transactions contemplated by the Merger Agreement are subject to the satisfaction, at or prior to the closing of the Merger, of each of the following conditions:

Conditions to Obligations of SWN

The obligations of SWN to consummate the transactions to be performed by SWN in connection with the closing is subject to the satisfaction or waiver, at or prior to the closing date, of each of the following conditions:

Conditions to Obligations of Indigo

The obligation of Indigo to consummate the transactions to be performed by Indigo in connection with the closing is subject to the satisfaction or waiver, at or prior to the closing date, of each of the following conditions:

Quorum and Required Vote for Proposals for the Special Meeting

A quorum of SWN’s shareholders is necessary to hold a valid meeting. A quorum will be present at the Special Meeting if the holders of a majority of the outstanding shares entitled to vote as of the close of business on the record date are present in person or represented by proxy at the Special Meeting. Abstentions will count as present for the purposes of establishing a quorum. Broker non-votes will be counted for the purposes of determining the existence of a quorum at the Special Meeting if a shareholder instructs its bank, broker or other nominee to vote its shares on any proposal. If a shareholder fails to instruct its bank, broker or nominee to vote its shares on any proposal, and such bank, broker or nominee exercises its authority to vote in its discretion on the Authorized Share Increase Proposal, then the shares voted by such bank, broker or nominee on the Authorized Share Increase Proposal will be counted for the purposes of determining the existence of a quorum at the Special Meeting.

Assuming a quorum is present, approval of the Stock Issuance Proposal requires the affirmative vote of the holders of a majority of the shares of Common Stock present in person or represented by proxy at the Special Meeting and entitled to vote thereat. Accordingly, with respect to a holder of shares of Common Stock who is present in person or represented by proxy at the Special Meeting, such shareholder’s abstention from voting or the failure of a holder of shares of Common Stock to vote will have the same effect as a vote “AGAINST” the Stock Issuance Proposal. The failure of a holder of shares of Common Stock who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to the bank, broker or other nominee also will have the same effect as a vote “AGAINST” the Stock Issuance Proposal if such bank, broker or other nominee exercises

its authority to vote in its discretion on the Authorized Share Increase Proposal. Additionally, if a holder of shares of Common Stock instructs its bank, broker or other nominee regarding the Authorized Share Increase Proposal or the Adjournment Proposal but not the Stock Issuance Proposal, such broker non-vote will have the same effect as voting “AGAINST” the Stock Issuance Proposal.

Approval of the Authorized Share Increase Proposal requires the affirmative vote of the holders of a majority of the outstanding shares of Common Stock entitled to vote on the proposal. Accordingly, an abstention from a holder of shares of Common Stock will have the same effect as a vote “AGAINST” the Authorized Share Increase Proposal. The failure to instruct your bank, broker or other nominee how you wish to vote your shares with respect to the Authorized Share Increase Proposal will permit such bank, broker or other nominee to exercise its authority to vote in its discretion on the Authorized Share Increase Proposal.

Approval of the Adjournment Proposal requires the affirmative vote of the holders of a majority of the shares of Common Stock present in person or represented by proxy at the Special Meeting and entitled to vote thereat. Accordingly, with respect to a holder of shares of Common Stock who is present in person or represented by proxy at the Special Meeting, such shareholder’s abstention from voting or the failure of a holder of shares of Common Stock to vote will have the same effect as a vote “AGAINST” the Adjournment Proposal. The failure of a holder of shares of Common Stock who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to the bank, broker or other nominee also will have the same effect as a vote “AGAINST” the Adjournment Proposal if such bank, broker or other nominee exercises its authority to vote in its discretion on the Authorized Share Increase Proposal. Additionally, if a holder of shares of Common Stock instructs its bank, broker or other nominee regarding the Stock Issuance Proposal or the Authorized Share Increase Proposal, but not the Adjournment Proposal, such broker non-vote will have the same effect as voting “AGAINST” the Adjournment Proposal. Unless there is a quorum, the presiding officer of the Special Meeting may also adjourn the Special Meeting.

The Merger is conditioned on, among other things, the approval of the Stock Issuance Proposal at the Special Meeting. The Merger is not conditioned on the approval of the Authorized Share Increase Proposal.

It is important for you to note that, in the event that the Stock Issuance Proposal does not receive the requisite vote for approval, SWN will not consummate the Merger and may be required to pay a termination fee to Indigo in connection with the termination of the Merger Agreement as a result of failure to receive the requisite vote for approval.

Opinion of SWN’s Financial Advisor

Goldman Sachs delivered its opinion to the Board that, as of June 1, 2021, and based upon and subject to the factors and assumptions set forth therein, the aggregate merger consideration consisting of 339,270,568 shares of Common Stock and $400,000,000 in cash, as it may be adjusted pursuant to Section 2.9, Section 3.1, Section 4.1, Article V and Section 6.1 of the Merger Agreement (the “aggregate merger consideration”), to be paid by SWN for all of the Indigo Units pursuant to the Merger Agreement was fair from a financial point of view to SWN.

The full text of the written opinion of Goldman Sachs, dated June 1, 2021, which sets forth assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached as Annex D. Goldman Sachs provided advisory services and its opinion for the information and assistance of the Board in connection with its consideration of the Merger. The Goldman Sachs opinion is not a recommendation as to how any holder of shares of Common Stock should vote with respect to the Merger or any other matter. Pursuant to an engagement letter between SWN and Goldman Sachs, SWN has agreed to pay Goldman Sachs a transaction fee of $15,000,000, all of which is contingent upon consummation of the Merger. Goldman Sachs may receive an additional fee of up to $3,000,000 at SWN’s discretion.

For more information, please see “Proposal No. 1—Approval of the Issuance of Common Stock in Connection with the Merger—Background of the Merger—Opinion of SWN’s Financial Advisor” on page 106 of this proxy statement and Annex D to this proxy statement.

Recommendation to the SWN Shareholders

The Board believes that each of the Stock Issuance Proposal, the Authorized Share Increase Proposal and the Adjournment Proposal is in the best interests of SWN and its shareholders and unanimously recommends that the shareholders vote “FOR” the Stock Issuance Proposal, “FOR” the Authorized Share Increase Proposal and “FOR” the Adjournment Proposal.

Risk Factors

In evaluating the Merger and the proposals to be considered and voted on at the Special Meeting, you should carefully review and consider the risk factors set forth under the section entitled “Risk Factors” beginning on page 54 of this proxy statement. The occurrence of one or more of the events or circumstances described in that section, alone or in combination with other events or circumstances, may have a material adverse effect on (i) the ability of SWN and Indigo to complete the Merger and (ii) the business, cash flows, financial condition and results of operations of SWN or Indigo prior to the consummation of the Merger.

SELECTED HISTORICAL FINANCIAL INFORMATION OF SWN

The following information has been derived from SWN’s unaudited consolidated financial statements as of and for the three-month periods ended March 31, 2021 and 2020 and SWN’s audited consolidated financial statements as of and for each of the years in the three-year period ended December 31, 2020. The following information is only a summary and does not provide all of the information contained in SWN’s financial statements.

The unaudited consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of SWN’s management, include all adjustments necessary for a fair statement of the information set forth therein. The results of interim periods are not necessarily indicative of results that may be expected for the full year or any future periods.

In addition, the following information includes the results of Montage from November 13, 2020, the closing date of the Montage Merger. As a result, the comparability of the periods ended March 31, 2021 and December 31, 2020 to prior periods could be impacted as a result of the Montage Merger.

SELECTED HISTORICAL FINANCIAL INFORMATION OF INDIGO

The following information as of December 31, 2020 and 2019, and for each of the years in the two-year period ended December 31, 2020, has been derived from Indigo’s audited consolidated financial statements and accompanying notes contained in SWN’s Current Report on Form 8-K filed on July 2, 2021, which is incorporated by reference into this proxy statement. The following information as of March 31, 2021 and for the three-month periods ended March 31, 2021 and 2020 have been derived from Indigo’s unaudited consolidated financial statements contained in SWN’s Current Report on Form 8-K filed on July 2, 2021. The following information is only a summary and does not provide all of the information contained in Indigo’s financial statements.

The unaudited consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of Indigo’s management, include all adjustments necessary for a fair statement of the information set forth therein. The results of interim periods are not necessarily indicative of results that may be expected for the full year or any future periods.

SELECTED UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

The following table presents summary unaudited pro forma condensed combined financial information about SWN’s financial condition and results of operations on a pro forma basis giving effect to the Merger and, as applicable, the Montage Merger and certain related transactions, as set forth in the unaudited pro forma financial statements incorporated in this proxy statement by reference.

The summary unaudited pro forma condensed combined financial information is derived from, and should be read in conjunction with, SWN’s consolidated financial statements and related notes incorporated by reference into this proxy statement, and the consolidated financial statements and related notes of Indigo incorporated by reference in this proxy statement, together with the more detailed information as set forth in the unaudited pro forma financial statements and related notes included in this proxy statement. The summary unaudited pro forma condensed combined financial information set forth below has been presented for informational purposes only and is not necessarily indicative of what the combined financial condition or results of operations actually would have been had the applicable transaction been completed as of the dates indicated. In addition, the summary unaudited pro forma condensed combined financial information presented below does not purport to project the combined financial condition or operating results for any future period.

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL STATEMENTS

Acquisition of Indigo Natural Resources LLC

On June 1, 2021, Southwestern Energy Company (“Southwestern”) entered into an Agreement and Plan of Merger with Ikon Acquisition Company, LLC (“Ikon”), Indigo Natural Resources LLC (“Indigo”) and Ibis Unitholder Representative LLC (the “Indigo Merger Agreement”). Pursuant to the terms of the Indigo Merger Agreement, Indigo will merge with and into Ikon, a subsidiary of Southwestern, with Indigo surviving the merger (the “Indigo Merger”). The outstanding equity interests in Indigo will be cancelled and converted into the right to receive (i) $400 million in cash consideration, and (ii) 339,270,568 shares of Southwestern common stock, in each case, subject to adjustment as provided in the Indigo Merger Agreement. Additionally, Southwestern will assume $700 million in aggregate principal amount of 5.375% Senior Notes due 2029 of Indigo (the “Indigo Notes”).

Acquisition of Montage Resources LLC

On November 13, 2020, pursuant to the Agreement and Plan of Merger, dated as of August 12, 2020, by and between Southwestern and Montage Resources Corporation (“Montage”), Southwestern completed its previously announced acquisition of Montage, by means of a merger of Montage with and into Southwestern, with Southwestern continuing as the surviving corporation (the “Montage Merger” and, together with the Indigo Merger, the “Mergers”).

In exchange for each share of Montage common stock, Montage shareholders received 1.8656 shares of Southwestern common stock, plus cash in lieu of any fractional share of Southwestern common stock that otherwise would have been issued, based on an average price of $3.05 per share of Southwestern common stock on the NYSE on November 13, 2020. Approximately 69.7 million total shares were issued to Montage shareholders and its management team as consideration for the Montage Merger.

Additionally, in August 2020, Southwestern completed an underwritten public offering of 63.25 million shares of common stock with an offering price to the public of $2.50 per share, with net proceeds from the offering totaling $152 million after deducting underwriting discounts and offering expenses (the “Equity Offering”). Also in August 2020, Southwestern completed an underwritten public offering of $350 million aggregate principal amount of 8.375% senior notes due 2028 (the “Debt Offering”). The net proceeds from the Debt Offering, after deducting the underwriting discount and offering expenses, were approximately $345 million. Southwestern used the net proceeds from the Debt Offering, together with the net proceeds received from the Equity Offering and borrowings under Southwestern’s credit facility, to fund the redemption of $510 million aggregate principal amount of Montage’s outstanding 8.875% Senior Notes due 2023 (the “Montage Notes”) and to pay off of the outstanding Montage credit facility balance and all related accrued interest in connection with the closing of the Montage Merger.

Unaudited Pro Forma Condensed Combined Financial Statements

The following unaudited pro forma condensed combined financial statements are derived from the historical consolidated financial statements of Southwestern and Indigo and from the historical financial activity of Montage through November 13, 2020, the closing date of the Montage Merger, and have been adjusted to reflect 1) the Equity Offering and the Debt Offering and the use of the proceeds therefrom as described above and 2) the Indigo Merger, as described above.

The proposed Indigo Merger will be accounted for using the acquisition method of accounting with Southwestern identified as the acquirer. Under the acquisition method of accounting, Southwestern will record assets acquired and liabilities assumed at their respective acquisition date fair values at the effective time of the Indigo Merger.

Certain historical amounts of Montage and Indigo have been reclassified to conform to Southwestern’s financial statement presentation. The unaudited pro forma condensed combined balance sheet as of March 31, 2021 gives effect to the Indigo Merger as if the transaction had been completed on March 31, 2021. The unaudited pro forma condensed combined statements of operations for the year ended December 31, 2020 and the three months ended March 31, 2021 give effect to the Mergers, the Equity Offering and the Debt Offering as if each transaction had been completed on January 1, 2020.

The unaudited pro forma condensed combined financial statements reflect the following Merger-related pro forma adjustments, based on available information and certain assumptions that Southwestern believes are reasonable:

Assumptions and estimates underlying the pro forma adjustments are described in the accompanying notes, which should be read in conjunction with the unaudited pro forma condensed combined financial statements. In Southwestern’s opinion, all adjustments that are necessary to present fairly the pro forma information have been made. The historical consolidated financial statements have been adjusted in the unaudited pro forma condensed combined financial statements to give effect to the Mergers, the Equity Offering and the Debt Offering along with the use of proceeds therefrom. These adjustments are directly attributable to the Mergers, factually supportable and, with respect to the unaudited pro forma condensed combined statements of operations, expected to have a continuing impact on the combined results of Southwestern following the Mergers.

The assets acquired and liabilities assumed from Montage were recorded at their preliminary estimated fair values at the date of the Montage Merger. Although the purchase price allocation for Montage is substantially complete as of the date of this filing, there may be further adjustments to Montage’s natural gas and oil properties as the studies necessary to determine the fair value are finalized. These amounts will be finalized no later than one year from the acquisition date. There have been no material changes to the allocation presented in Southwestern’s Form 10-Q for the three-month period ended March 31, 2021.

The acquisition method of accounting as it relates to the Indigo Merger is dependent upon certain valuations and other studies that, as of the date hereof, have yet to commence or progress to a stage where there is sufficient information for a definitive measure. As of the date of this proxy statement, Southwestern has performed a preliminary valuation analysis of the fair value of Indigo’s assets to be acquired and liabilities to be assumed and has made certain adjustments to the historical book values of the assets and liabilities of Indigo to reflect preliminary estimates of the fair value necessary to prepare the unaudited pro forma condensed combined financial statements. A final determination of the fair value of Indigo’s assets and liabilities, including potential intangible assets with both indefinite or finite lives, will be based on the actual net tangible and intangible assets and liabilities of Indigo that exist as of the closing date of the Indigo Merger and, therefore, cannot be made prior to the completion of the Indigo Merger. In addition, the value of the consideration to be paid by Southwestern upon the consummation of the Indigo Merger will be determined based on the closing price of Southwestern common stock on the closing date of the Indigo Merger. As a result of the foregoing, the pro forma adjustments are preliminary and are subject to change as additional information becomes available and as additional analysis

is performed. The preliminary pro forma adjustments have been made solely for the purpose of providing the unaudited pro forma condensed combined financial statements presented below. Southwestern estimated the fair value of Indigo’s assets and liabilities based on discussions with Indigo’s management, preliminary valuation studies, due diligence, and information presented in Indigo’s historical financial statements. Until the Indigo Merger is completed, both companies are limited in their ability to share certain information. Any increases or decreases in the fair value of assets acquired and liabilities assumed upon completion of the final valuations will result in adjustments to the unaudited pro forma condensed combined balance sheet and/or statements of operations. The final purchase price allocation may be materially different than that reflected in the pro forma purchase price allocation presented herein.

The unaudited pro forma condensed combined financial information is not intended to represent what Southwestern’s financial position or results of operations would have been had the Mergers actually been consummated on the assumed dates nor does it purport to project the future operating results or financial position of the combined company following the Indigo Merger. The unaudited pro forma condensed combined financial information does not reflect future events that may occur after the Indigo Merger, including, but not limited to, the anticipated realization of ongoing savings from potential operating efficiencies, asset dispositions, cost savings, or economies of scale that the combined company may achieve with respect to the combined operations. Specifically, the unaudited pro forma condensed combined statements of operations do not include projected synergies expected to be achieved as a result of the Mergers and any associated costs that may be required to be incurred to achieve the identified synergies. The unaudited pro forma condensed combined statements of operations also exclude the effects of transaction costs associated with the Indigo Merger, costs associated with any restructuring, integration activities, and asset dispositions that may result from the Mergers. Further, the unaudited pro forma condensed combined financial statements do not reflect the effect of any regulatory actions that may impact the results of the combined company following the Mergers.

The unaudited pro forma condensed combined financial statements should be read in conjunction with the historical consolidated financial statements and accompanying notes contained in Southwestern’s Annual Report on Form 10-K for the year ended December 31, 2020, Southwestern’s Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2021, and Indigo’s historical financial statements and accompanying notes as of and for the year ended December 31, 2020 and as of and for the three-month period ended March 31, 2021 included in Southwestern’s Current Report on Form 8-K filed on July 2, 2021, which is incorporated by reference into this proxy statement.