Sec Form 4 Filing - DEMETRIOU STEVEN J. @ Amentum Holdings, Inc. - 2024-10-02

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 DEMETRIOU STEVEN J. 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 _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Executive Chair (Last) (First) (Middle) C/O AMENTUM HOLDINGS, INC., 4800 WESTFIELDS BOULEVARD, SUITE 400 3. Date of Earliest Transaction (MM/DD/YY) 10/02/2024 (Street) CHANTILLY, VA20151 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

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 Restricted Stock Units ( 1 ) ( 1 ) 10/02/2024 A 43,396 ( 2 ) ( 2 ) Common Stock 43,396 $ 0 43,396 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other DEMETRIOU STEVEN J. C/O AMENTUM HOLDINGS, INC. 4800 WESTFIELDS BOULEVARD, SUITE 400 CHANTILLY, VA20151 X Executive Chair Signatures /s/ Paul W. Cobb, Jr.Attorney-in-fact 10/04/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )These restricted stock units ("RSUs") were originally granted by Jacobs Solutions Inc. ("Jacobs") and, pursuant to the terms of the Employee Matters Agreement, dated as of November 20, 2023, by and among Jacobs, the Issuer and Amentum Parent Holdings LLC, as amended from time to time, were converted into RSUs with respect to Issuer common stock with adjustments made to the number of shares subject to the award in order to preserve the award's value. The conversion ratio was determined based on the closing price per share of Jacobs common stock on September 27, 2024 divided by the average of the volume-weighted average prices of the Issuer's common stock on the New York Stock Exchange for the period beginning on September 30, 2024 and ending on October 2, 2024. ( 2 )This award will vest in full on November 17, 2025, subject to the reporting person's continued service through such date.

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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