Sec Form 4 Filing - Cormorant Asset Management, LP @ Icosavax, Inc. - 2021-08-02

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Cormorant Asset Management, LP 2. Issuer Name and Ticker or Trading Symbol Icosavax, Inc. [ ICVX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner _____ Officer (give title below) X __ Other (specify below) Former 10% Owner (Last) (First) (Middle) 200 CLARENDON STREET, 52ND FLOOR, 3. Date of Earliest Transaction (MM/DD/YY) 08/02/2021 (Street) BOSTON, MA02116 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 08/02/2021 C 426,393 A 426,393 I See Footnotes ( 2 ) ( 3 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series B-1 Convertible Preferred Stock ( 1 ) 08/02/2021 C 426,393 ( 1 ) ( 1 ) Common Stock 426,393 ( 1 ) 0 I See Footnotes ( 2 ) ( 4 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Cormorant Asset Management, LP 200 CLARENDON STREET, 52ND FLOOR BOSTON, MA02116 Former 10% Owner Chen Bihua C/O CORMORANT ASSET MANAGEMENT, LLC 200 CLARENDON STREET, 52ND FLOOR BOSTON, MA02116 Former 10% Owner Cormorant Global Healthcare Master Fund, LP 200 CLARENDON STREET, 52ND FLOOR BOSTON, MA02116 Former 10% Owner Cormorant Private Healthcare Fund III LP 200 CLARENDON STREET, 52ND FLOOR BOSTON, MA02116 Former 10% Owner Signatures /s/ CORMORANT ASSET MANAGEMENT, LP By : Cormorant Asset Management GP, LLC, its General Partner, By: Bihua Chen, Managing Member 08/04/2021 Signature of Reporting Person Date /s/ CORMORANT GLOBAL HEALTHCARE MASTER FUND, LP, By: Cormorant Global Healthcare GP, LLC, its General Partner By: Bihua Chen, Managing Member 08/04/2021 Signature of Reporting Person Date /s/ Bihua Chen 08/04/2021 Signature of Reporting Person Date /s/ CORMORANT PRIVATE HEALTHCARE FUND III, LP By: Cormorant Private Healthcare GP III, LLC, its General Partner By: Bihua Chen, Managing Member 08/04/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Shares of Series B-1 Convertible Preferred Stock were convertible at any time at the holder's election, without payment of additional consideration. Such shares had no expiration date but converted into Common Stock automatically upon the closing of the Issuer's initial public offering. ( 2 )Shares reported herein are held by Cormorant Global Healthcare Master Fund, LP (the "Master Fund"), Cormorant Private Healthcare Fund III, LP ("Fund III") and a managed account (the "Account"). Cormorant Asset Management, LP ("Cormorant") serves as the investment manager of the Master Fund and Fund III. Bihua Chen serves as manager of the general partner of Cormorant. Each of the Reporting Persons disclaims beneficial ownership of the shares reported herein except to the extent of its or her pecuniary interest therein, and the filing of this Form 4 shall not be construed as an admission that any of the Reporting Persons is the beneficial owner of any such shares for purposes of Section 16(a) of the Securities Exchange Act of 1934 or for any other purpose. ( 3 )Represents (i) 93,380 shares of Common Stock held by the Master Fund, (ii) 325,445 shares of Common Stock held by Fund III, and (iii) 7,568 shares held by the Account. ( 4 )The Series B-1 Convertible Preferred Stock represented, on an as-converted basis, (i) 93,380 shares of Common Stock held by the Master Fund, (ii) 325,445 shares of Common Stock held by Fund III, and (iii) 7,568 shares held by the Account

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