[POS AM] DYNAVAX TECHNOLOGIES CORP SEC Filing

As filed with the Securities and Exchange Commission on February 10, 2026

Registration No. 333-273674

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 1 TO

FORM S-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Dynavax Technologies Corporation

(Exact name of registrant as specified in its charter)

Delaware		33-0728374
(State or other jurisdiction of incorporation or organization)		(I.R.S. Employer Identification No.)

2100 Powell Street, Suite 720

Emeryville, CA 94608

(510) 665-4618

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Thomas Grenier

Vice President

Dynavax Technologies Corporation

2100 Powell Street, Suite 720

Emeryville, CA 94608

(510) 665-4618

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Michael J. Aiello, Esq.

Sachin Kohli, Esq.

Weil, Gotshal & Manges LLP

767 Fifth Avenue

New York, New York 10153

(212) 310-8000

Approximate date of commencement of proposed sale to the public: not applicable.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. ☐

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, 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, please 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(c) 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 registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. ☒

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ☐

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. ☐

DEREGISTRATION OF UNSOLD SECURITIES

This Post-Effective Amendment relates to the Registration Statement on Form S-3 (File No. 333-273674) (the “Registration Statement”) filed by Dynavax Technologies Corporation, a Delaware corporation (the “Company”), with the Securities and Exchange Commission (the “Commission”) on August 3, 2023. The Registration Statement pertains to the registration of (i) up to $120,000,000 of the Company’s common stock that may be issued and sold from time to time under a sales agreement with Cowen and Company, LLC, as amended and (ii) an indeterminate number of shares of common stock, shares of preferred stock, debt securities and warrants of the Company.

Pursuant to the Agreement and Plan of Merger, dated as of December 23, 2025 (the “Merger Agreement”), by and among the Company, Sanofi, a French société anonyme (“Sanofi”) and Samba Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of Genzyme (“Purchaser”), Purchaser merged with and into the Company with the Company surviving the merger as an indirect wholly owned subsidiary of Sanofi. The merger became effective on February 10, 2026, upon the filing of the certificate of merger with the Secretary of State of the State of Delaware.

As a result of the transactions contemplated by the Merger Agreement, the Company has terminated all offerings of its securities pursuant to the Registration Statement and, in accordance with undertaking made by the Company in the Registration Statement to remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering, hereby removes and withdraws from registration all securities registered pursuant to the Registration Statement that remain unsold as of the date hereof. The Registration Statement is hereby amended, as appropriate, to reflect the deregistration of such securities.

SIGNATURE

Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused the Post-Effective Amendment to the Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Emeryville, State of California, on February 10, 2026.

DYNAVAX TECHNOLOGIES CORPORATION
By:		/s/ Thomas Grenier
Name:		Thomas Grenier
Title:		Vice President

Pursuant to Rule 478 of the Securities Act of 1933, as amended, no other person is required to sign this Post-Effective Amendment to the Registration Statement.