SEC Form POS AM filed by Icosavax Inc.

As filed with the Securities and Exchange Commission on February 20, 2024

Registration No. 333-266894

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Post-Effective Amendment No. 1 TO

Form S-3 Registration Statement (RegISTRATION No. 333-266894)

under the securities act of 1933

ICOSAVAX, INC.

(Exact name of registrant as specified in its charter)

David E. White

Vice President

Icosavax, Inc.

1930 Boren Avenue, Suite 1000

Seattle, Washington 98101

(206) 737-0085

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

Copies to:

Approximate date of commencement of proposed sale to the public: Not applicable. Removal from registration of securities that were not sold pursuant to the above referenced registration statement.

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

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. x

DEREGISTRATION OF SECURITIES

This Post-Effective Amendment (the “Post-Effective Amendment No. 1”) relates to the following registration statement on Form S-3 filed with the Securities and Exchange Commission (the “SEC”) by Icosavax, Inc., a Delaware corporation (the “Registrant”):

The Registrant is filing this Post-Effective Amendment No. 1 to the Registration Statement to deregister all securities that remain unsold under the Registration Statement.

On February 19, 2024, pursuant to the terms of an Agreement and Plan of Merger, dated as of December 11, 2023 (the “Merger Agreement”), by and among the Registrant, AstraZeneca Finance and Holdings Inc., a Delaware corporation (“Parent”), and Isochrone Merger Sub Inc., a Delaware corporation and a wholly owned subsidiary of Parent (“Merger Sub”), Merger Sub merged with and into the Registrant, with the Registrant surviving the merger as a wholly owned subsidiary of Parent (the “Merger”).

As a result of the Merger, the Registrant has terminated any and all offerings of its securities pursuant to the Registration Statement. In accordance with an undertaking made by the Registrant in the Registration Statement to remove from registration, by means of a post-effective amendment, any of the securities registered under the Registration Statement that remain unissued at the termination of the offering, the Registrant hereby removes from registration all securities registered but unsold under such Registration Statement, if any, as of the date hereof.

Signatures

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 the requirements for filing on Form S-3 and has duly caused this Post-Effective Amendment No. 1 to the Registration Statement on Form S-3 to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Wilmington, State of Delaware on February 20, 2024.

Note: No other person is required to sign this Post-Effective Amendment No. 1 to the Registration Statement on Form S-3, in reliance upon Rule 478 under the Securities Act of 1933, as amended.