Sec Form 4 Filing - Katabi Maha @ RayzeBio, Inc. - 2023-09-19

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 Katabi Maha 2. Issuer Name and Ticker or Trading Symbol RayzeBio, Inc. [ RYZB] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O RAYZEBIO, INC., 5505 MOREHOUSE DRIVE, SUITE 300 3. Date of Earliest Transaction (MM/DD/YY) 09/19/2023 (Street) SAN DIEGO, CA92121 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 09/19/2023 C 973,653 A 973,653 I See footnote ( 2 ) Common Stock 09/19/2023 C 973,653 A 973,653 I See footnote ( 3 ) Common Stock 09/19/2023 P( 4 ) 236,111 A $ 18 1,209,764 I See footnote ( 2 ) Common Stock 09/19/2023 P( 4 ) 236,111 A $ 18 1,209,764 I See footnote ( 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 D Convertible Preferred Stock ( 1 ) 09/19/2023 C 973,653 ( 1 ) ( 1 ) Common Stock 973,653 ( 1 ) 0 I By Sofinnova Venture Partners X, L.P. ( 2 ) Series D Convertible Preferred Stock ( 1 ) 09/19/2023 C 973,653 ( 1 ) ( 1 ) Common Stock 973,653 ( 1 ) 0 I By Sofinnova Venture Partners XI, L.P. ( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Katabi Maha C/O RAYZEBIO, INC. 5505 MOREHOUSE DRIVE, SUITE 300 SAN DIEGO, CA92121 X Signatures /s/ Jeff Woodley, Attorney-in-fact 09/21/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Every 5.141 shares of Series D Convertible Preferred Stock (the "Preferred Stock") automatically converted into one share of Common Stock upon the closing of the Issuer's initial public offering. Share numbers give effect to such conversion. The Preferred Stock had no expiration date. ( 2 )The shares are held by Sofinnova Venture Partners X, L.P. ("SVP X"). Sofinnova Management X, L.P. ("SM X LP"), the general partner of SVP X, may be deemed to have sole voting and dispositive power over these shares, and Sofinnova Management X-A, L.L.C. ("SM X LLC"), the general partner of SM X LP, may be deemed to have sole voting and dispositive power over these shares. Dr. James I. Healy and Dr. Maha Katabi, the managing members of SM X LLC, may be deemed to have shared power to vote and dispose of these shares. Such entities and individuals disclaim beneficial ownership of such shares except to the extent of their pecuniary interest therein. ( 3 )The shares are held by Sofinnova Venture Partners XI, L.P. ("SVP XI"). Sofinnova Management XI, L.P. ("SM XI LP"), the general partner of SVP XI, may be deemed to have sole voting and dispositive power over these shares, and Sofinnova Management XI, L.L.C. ("SM XI LLC"), the general partner of SM XI LP, may be deemed to have sole voting and dispositive power over these shares. Dr. James I. Healy and Dr. Maha Katabi, the managing members of SM XI LLC, may be deemed to have shared power to vote and dispose of these shares. Such entities and individuals disclaim beneficial ownership of such shares except to the extent of their pecuniary interest therein. ( 4 )The shares were purchased in the Issuer's initial public offering.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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