ZGNX Zogenix Inc

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE TO

(Rule 14d-100)

TENDER OFFER STATEMENT UNDER SECTION 14(D)(1) OR 13(E)(1)

OF THE SECURITIES EXCHANGE ACT OF 1934

ZOGENIX, INC.

(Name of Subject Company (Issuer))

Zinc Merger Sub, Inc.

an indirect wholly owned subsidiary of

UCB S.A.

(Names of Filing Persons (Offerors))

Common Stock, par value $0.001 per share

(Title of Class of Securities)

98978L204

(CUSIP Number of Class of Securities (Underlying Common Stock))

Bill Silbey

Executive Vice President and General Counsel

UCB S.A.

Allée de la Recherche, 60

1070 Brussels

Tel: 32 2 559 99 99

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications on Behalf of Filing Persons)

Copies to:

J. D. Weinberg, Esq.

Kyle Rabe, Esq.

Covington & Burling LLP

The New York Times Building

620 Eighth Avenue

New York, NY 10018-1405

+1 (212) 841 1000

Calculation of Filing Fee

Check the appropriate boxes below to designate any transactions to which the statement relates:

Check the following box if the filing is a final amendment reporting the results of the tender offer:  ☐

If applicable, check the appropriate box(es) below to designate the appropriate rule provision(s) relied upon:

This Tender Offer Statement on Schedule TO (together with any amendments and supplements hereto, this “Schedule TO”) is filed by Zinc Merger Sub, Inc., a Delaware corporation (“Purchaser”) and an indirect wholly owned subsidiary of UCB S.A., a société anonyme formed under the laws of Belgium (“Parent”), and Parent. This Schedule TO relates to the offer by Purchaser to purchase all of the outstanding shares of common stock, par value $0.001 per share (the “Shares”), of Zogenix, Inc., a Delaware corporation (“Zogenix”), in exchange for (i) $26.00 per Share, net to the seller in cash, without interest and less any applicable withholding taxes (the “Cash Amount”), plus (ii) one non-transferable contingent value right per Share (each, a “CVR”), which CVR represents the right to receive a contingent payment of $2.00, net to the seller in cash, without interest and less any applicable tax withholding, which amount will become payable, if at all, if a specified milestone is achieved on or prior to December 31, 2023 (the Cash Amount plus one CVR, collectively, or any greater amount per Share that may be paid pursuant to the Offer, being hereinafter referred to as the “Offer Price”), upon the terms and subject to the conditions set forth in the Offer to Purchase and in the related Letter of Transmittal, copies of which are attached hereto as Exhibits (a)(1)(A) and (a)(1)(B), respectively.

All information contained in the Offer to Purchase (including Schedule I to the Offer to Purchase) and the accompanying Letter of Transmittal is hereby expressly incorporated herein by reference in response to Items 1 through 9 and Item 11 of this Schedule TO.

The Agreement and Plan of Merger dated as of January 18, 2022 (as it may be amended, supplemented or otherwise modified from time to time, the “Merger Agreement”), among Zogenix, Parent and Purchaser, a copy of which is attached as Exhibit (d)(1) hereto, is incorporated herein by reference with respect to Items 4, 5, 6 and 11 of this Schedule TO.

The information set forth in the “Summary Term Sheet” of the Offer to Purchase is incorporated herein by reference.

(a) The name of the subject company and the issuer of the securities to which this Schedule TO relates is Zogenix, Inc., a Delaware corporation. Zogenix’s principal executive offices are located at 5959 Horton Street, Suite 500, Emeryville, CA 94608. Zogenix’s telephone number is (510) 550-8300.

(b) This Schedule TO relates to the outstanding Shares. Zogenix has advised Purchaser and Parent that, as of January 27, 2022 (the most recent practicable date): (i) 56,125,822 shares of Zogenix common stock were issued and outstanding, (ii) 6,637,422 shares of Zogenix common stock were subject to outstanding Zogenix stock options, (iii) 804,112 shares of Zogenix common stock were subject to outstanding Zogenix restricted stock unit awards, (iv) 300,255 shares of Zogenix common stock were subject to outstanding Zogenix performance stock unit awards (at maximum), and (v) rights to purchase a maximum of 385,515 shares of Zogenix common stock pursuant to Zogenix’s 2010 Employee Stock Purchase Plan were outstanding.

(c) The information set forth in Section 6 (entitled “Price Range of Shares; Dividends on the Shares”) of the Offer to Purchase is incorporated herein by reference.

(a) - (c) This Schedule TO is filed by Purchaser and Parent. The information set forth in Section 8 (entitled “Certain Information Concerning Parent and Purchaser”) of the Offer to Purchase and Schedule I to the Offer to Purchase is incorporated herein by reference.

(a)(1)(i) - (viii), (xii), (a)(2)(i) - (iv), (vii) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

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(a)(1)(ix) - (xi), (a)(2)(v) - (vi) Not applicable.

(a), (b) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

(a), (c)(1) - (7) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

(a), (b), (d) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

(a) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

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(b) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

(a) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

Not applicable.

(a)(1) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

(a)(2) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

(a)(3) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

(a)(4) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

(a)(5) The information set forth in the following sections of the Offer to Purchase is incorporated herein by reference:

(c) The information set forth in the Offer to Purchase is incorporated herein by reference.

3

Not applicable.

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SIGNATURES

After due inquiry and to the best knowledge and belief of the undersigned, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Date: February 1, 2022

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