[Form 4] Amentum Holdings, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Amentum Holdings (AMTM): Form 4 insider activity. The Chief Growth Officer reported the vesting and settlement of 4,838 restricted stock units into common stock on November 6, 2025. To cover taxes, 1,621 shares were withheld at $21.79 per share (Code F). Following these transactions, the reporting person directly holds 3,217 shares of common stock and 9,678 RSUs remain outstanding. Each RSU represents the right to receive one share.

SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
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hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Mullen Sean Thomas

(Last) (First) (Middle)

C/O AMENTUM HOLDINGS, INC.

4800 WESTFIELDS BOULEVARD, SUITE 400

(Street)

CHANTILLY VA 20151

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Amentum Holdings, Inc. [ AMTM ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Growth Officer

3. Date of Earliest Transaction (Month/Day/Year)
11/06/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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	11/06/2025		M		4,838	A	(1)	4,838	D
Common Stock	11/06/2025		F		1,621(2)	D	$21.79	3,217	D

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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: 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	(3)	11/06/2025		M(1)			4,838	(4)	(4)	Common Stock	4,838	$0	9,678	D

Explanation of Responses:

1. Represents distribution of AMTM common stock upon vesting of restricted stock units.

2. Represents number of shares of AMTM common stock tendered for tax withholding upon vesting of restricted stock units.

3. Each restricted stock unit represents a contingent right to receive one share of AMTM common stock.

4. The restricted stock units awarded vested on November 6, 2025.

Remarks:

	/s/ Mark Esposito, Attorney-in-Fact	11/10/2025
	** Signature of Reporting Person	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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did AMTM report on Form 4?

The Chief Growth Officer reported vesting of 4,838 RSUs into common stock on November 6, 2025 and tax withholding of 1,621 shares at $21.79.

How many AMTM shares does the insider hold after the transaction?

The reporting person holds 3,217 shares of AMTM common stock directly after the transactions.

How many AMTM RSUs remain after the vesting event?

The Form 4 shows 9,678 restricted stock units remain beneficially owned following the vesting.

What does each AMTM RSU represent?

Each RSU represents a contingent right to receive one share of AMTM common stock upon vesting.

What was the tax withholding method and price on AMTM shares?

Shares were withheld to satisfy taxes (Code F), with 1,621 shares withheld at $21.79 per share.

Who is the reporting person’s role at AMTM?

The reporting person is an officer, serving as Chief Growth Officer.