Sec Form 3 Filing - Adiumentum Capital Fund I LP @ Atara Biotherapeutics, Inc. - 2024-09-03

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 Adiumentum Capital Fund I LP 2. Issuer Name and Ticker or Trading Symbol Atara Biotherapeutics, Inc. [ ATRA] 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) C/O CADWALADER, WICKERSHAM & TAFT LLP, 200 LIBERTY STREET 3. Date of Earliest Transaction (MM/DD/YY) 09/03/2024 (Street) NEW YORK, NY10281 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, par value $0.0001 per share 1,133,823 D ( 1 ) ( 2 )

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 Warrants (right to buy) $ 0.0001 09/03/2024 ( 3 ) Common Stock 150,193 ( 4 ) ( 5 ) D ( 1 ) ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Adiumentum Capital Fund I LP C/O CADWALADER, WICKERSHAM & TAFT LLP 200 LIBERTY STREET NEW YORK, NY10281 X X Adiumentum Capital Fund I GP LLC C/O CADWALADER, WICKERSHAM & TAFT LLP 200 LIBERTY STREET NEW YORK, NY10281 X X Ciongoli Gregory Austin C/O CADWALADER, WICKERSHAM & TAFT LLP 200 LIBERTY STREET NEW YORK, NY10281 X X Signatures Adiumentum Capital Fund I LP By: /s/ Gregory A. Ciongoli, Managing Partner 09/05/2024 Signature of Reporting Person Date Adiumentum Capital Fund I GP LLC By: /s/ Gregory A. Ciongoli, Managing Member 09/05/2024 Signature of Reporting Person Date /s/ Gregory A. Ciongoli 09/05/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )In addition to Adiumentum Capital Fund I LP, a limited partnership organized under the laws of Delaware ("Adiumentum"), this Form 3 is being filed jointly by Adiumentum Capital Fund I GP LLC, a limited liability company organized under the laws of Delaware and the general partner of Adiumentum ("Adiumentum GP"), and Gregory A. Ciongoli, a citizen of the United States of America and the managing member of Adiumentum GP, (together with Adiumentum and Adiumentum GP, the "Reporting Persons"). Each of the Reporting Persons has the same business address as Adiumentum and may be deemed to have a pecuniary interest in securities reported on this Form 3 (the "Subject Securities"). Each of the Reporting Persons disclaims any beneficial ownership of any of the Subject Securities, except to the extent of any pecuniary interest therein. ( 2 )Adiumentum may be deemed to have the shared power to vote or direct the vote of (and the shared power to dispose or direct the disposition of) all of the Subject Securities. Adiumentum GP, as the general partner of Adiumentum may be deemed to have the shared power to vote or direct the vote of (and the shared power to dispose or direct the disposition of) all the Subject Securities. Mr. Ciongoli, as the managing partner of Adiumentum, and as the managing member of Adiumentum GP, may be deemed to have the shared power to vote or direct the vote of (and the shared power to dispose or direct the disposition of) all the Subject Securities. ( 3 )The warrants do not expire. ( 4 )Pursuant to the terms of the warrants, the Issuer may not effect any exercise of any warrant, and a holder of a warrant does not have the right to exercise any portion of the warrant held by such holder, to the extent that, after giving effect to the attempted exercise set forth in a notice of exercise, such holder, together with such holder's affiliates and any other person whose beneficial ownership of common stock, par value $0.0001 per share (the "Common Stock"), of the Issuer would be aggregated with such holder's for the purposes of Section 13(d) of the Exchange Act, and the applicable regulations of the U.S. Securities and Exchange Commission (the "SEC"), including any "group" of which such holder is a member, would beneficially own a number of shares of Common Stock in excess of the Beneficial Ownership Limitation. ( 5 )The "Beneficial Ownership Limitation" is 19.99% of the shares of Common Stock then issued and outstanding, which percentage may be changed at a holder's election upon 61 days' notice to the Issuer.

Remarks: Mr. Ciongoli serves as a director on the Board of Directors of the Issuer and, as a result, the entities listed in these notes are directors by deputization for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the "Exchange Act").

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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