Sec Form 3 Filing - Amentum Joint Venture GP LLC @ Amentum Holdings, Inc. - 2024-09-27

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 Amentum Joint Venture GP LLC 2. Issuer Name and Ticker or Trading Symbol Amentum Holdings, Inc. [ AMTM] 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 GOLDBERG LINDSAY & CO. LLC, 630 FIFTH AVENUE, 30TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 09/27/2024 (Street) NEW YORK, NY10111 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 90,021,804 I By Amentum Joint Venture LP ( 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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Amentum Joint Venture GP LLC C/O GOLDBERG LINDSAY & CO. LLC 630 FIFTH AVENUE, 30TH FLOOR NEW YORK, NY10111 X X Amentum Joint Venture LP C/O GOLDBERG LINDSAY & CO. LLC 630 FIFTH AVENUE, 30TH FLOOR NEW YORK, NY10111 X X Signatures /s/ James C. Pickel, Jr., Authorized Signatory for Amentum Joint Venture GP LLC 09/27/2024 Signature of Reporting Person Date /s/ Eric Schondorf, Authorized Signatory for Amentum Joint Venture GP LLC 09/27/2024 Signature of Reporting Person Date /s/ James C. Pickel, Jr., Authorized Signatory for Amentum Joint Venture GP LLC, the general partner of Amentum Joint Venture LP 09/27/2024 Signature of Reporting Person Date /s/ Eric Schondorf, Authorized Signatory for Amentum Joint Venture GP LLC, the general partner of Amentum Joint Venture LP 09/27/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )This Form 3 is jointly filed by (i) Amentum Joint Venture GP LLC and (ii) Amentum Joint Venture LP. Amentum Joint Venture GP LLC is the general partner of Amentum Joint Venture LP and may be deemed to have indirect voting and investment control over the shares held by Amentum Joint Venture LP. The shares of the Issuer reported in this Form 3 are owned directly by Amentum Joint Venture LP as a result of the merger with Amazon Holdco Inc. in a Reverse Morris Trust transaction (the "RMT Transaction"), with the Issuer surviving and being renamed Amentum Holdings, Inc., pursuant to the merger agreement and separation and distribution agreement, each dated as of November 20, 2023, among, in each case, Jacobs Solutions, Inc., the Issuer, Amentum Parent Holdings LLC and Amentum Joint Venture LP, and as may be amended from time to time prior to the date hereof. ( 2 )Solely for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), the Reporting Persons may be deemed to be directors-by-deputization by virtue of the Reporting Persons' contractual right to nominate directors to the board of directors of the Issuer pursuant to the Stockholders' Agreement by and between Amentum Joint Venture LP and the Issuer, dated September 27, 2024, entered into in connection with the RMT Transaction. For purposes of the exemption under Rule 16b-3 promulgated under the Exchange Act, the Board approved the acquisition of any direct or indirect pecuniary interest of the shares of the Securities reported herein by the Reporting Persons.

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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