Sec Form 3 Filing - Fairmount Funds Management LLC @ Zenas BioPharma, Inc. - 2024-09-12

FORM 3 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 Fairmount Funds Management LLC 2. Issuer Name and Ticker or Trading Symbol Zenas BioPharma, Inc. [ ZBIO] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 200 BARR HARBOR DRIVE, SUITE 400 3. Date of Earliest Transaction (MM/DD/YY) 09/12/2024 (Street) WEST CONSHOHOCKEN, PA19428 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 287,915 I By Fairmount Healthcare Fund II LP ( 1 )

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 Seed Convertible Preferred Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 41,130 I By Fairmount Healthcare Fund II LP ( 1 ) Series A Convertible Preferred Stock ( 3 ) ( 3 ) ( 3 ) Common Stock 252,890 I By Fairmount Healthcare Fund II LP ( 1 ) Series B Convertible Preferred Stock ( 4 ) ( 4 ) ( 4 ) Common Stock 709,794 I By Fairmount Healthcare Fund II LP ( 1 ) Series C Convertible Preferred Stock ( 5 ) ( 5 ) ( 5 ) Common Stock 301,077 I By Fairmount Healthcare Fund II LP ( 1 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Fairmount Funds Management LLC 200 BARR HARBOR DRIVE SUITE 400 WEST CONSHOHOCKEN, PA19428 X X Fairmount Healthcare Fund II L.P. 200 BARR HARBOR DRIVE SUITE 400 WEST CONSHOHOCKEN, PA19428 X X Kiselak Tomas 200 BARR HARBOR DRIVE SUITE 400 WEST CONSHOHOCKEN, PA19428 X X Harwin Peter Evan 200 BARR HARBOR DRIVE SUITE 400 WEST CONSHOHOCKEN, PA19428 X X Signatures /s/ Tomas Kiselak, Managing Member of Fairmount Funds Management LLC 09/12/2024 Signature of Reporting Person Date /s/ Tomas Kiselak, Managing Member of Fairmount Healthcare Fund II LP 09/12/2024 Signature of Reporting Person Date /s/ Tomas Kiselak 09/12/2024 Signature of Reporting Person Date /s/ Peter Harwin 09/12/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Fairmount Funds Management LLC ("Fairmount") is the investment manager for Fairmount Healthcare Fund II L.P. ("Fund II"). The general partner of Fairmount is Fairmount Funds Management GP LLC ("Fairmount GP"), of which Peter Harwin and Tomas Kiselak are the managing members. Fairmount, Fairmount GP, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein. ( 2 )Each share of Series Seed Convertible Preferred Stock is convertible into shares of the Issuer's Common Stock on a 8.6831-for-1 basis and has no expiration date. The Series Seed Convertible Preferred Stock will automatically convert into common stock upon the closing of the Company's initial public offering. ( 3 )Each share of Series A Convertible Preferred Stock is convertible into shares of the Issuer's Common Stock on a 8.6831-for-1 basis and has no expiration date. The Series A Convertible Preferred Stock will automatically convert into common stock upon the closing of the Company's initial public offering. ( 4 )Each share of Series B Convertible Preferred Stock is convertible into shares of the Issuer's Common Stock on a 8.6831-for-1 basis and has no expiration date. The Series B Convertible Preferred Stock will automatically convert into common stock upon the closing of the Company's initial public offering. ( 5 )Each share of Series C Convertible Preferred Stock is convertible into shares of the Issuer's Common Stock on a 8.6831-for-1 basis and has no expiration date. The Series C Convertible Preferred Stock will automatically convert into common stock upon the closing of the Company's initial public offering.

Remarks: Fairmount may be deemed a director by deputization of the Issuer by virtue of the fact that Tomas Kiselak serves on the board of directors of the Issuer and is a Managing Member of Fairmount.

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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