Amentum (AMTM) Chief People Officer discloses RSU vesting and tax withholding shares

Rhea-AI Filing Summary

Amentum Holdings, Inc. Chief People Officer reported routine equity compensation activity involving company stock. On December 5, 2025, 2,721 restricted stock units were converted into the same number of shares of AMTM common stock as they vested. To cover taxes on this vesting, 1,392 shares of AMTM common stock were tendered at a price of $28.88 per share.

After these transactions, the officer directly beneficially owned 23,600 shares of AMTM common stock and held 5,444 restricted stock units, each representing a contingent right to receive one AMTM share. These reported movements reflect standard vesting and tax withholding mechanics rather than open-market buying or selling.

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

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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^*

Burton Darren

(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 People Officer

3. Date of Earliest Transaction (Month/Day/Year)
12/05/2025

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	12/05/2025		M		2,721	A	(1)	24,992	D
Common Stock	12/05/2025		F		1,392(2)	D	$28.88	23,600	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)	12/05/2025		M(1)			2,721	(4)	(4)	Common Stock	2,721	$0	5,444	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 December 5, 2025.

Remarks:

	/s/ Mark Esposito, Attorney-in-Fact	12/09/2025
	** 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 Amentum Holdings (AMTM) report in this Form 4?

The Chief People Officer reported the vesting of 2,721 restricted stock units, which were distributed as the same number of AMTM common shares, along with related tax withholding transactions.

How many Amentum (AMTM) shares were used for tax withholding?

The filing states that 1,392 shares of AMTM common stock were tendered to satisfy tax withholding obligations when the restricted stock units vested, at a price of $28.88 per share.

How many Amentum (AMTM) shares does the officer own after these transactions?

Following the reported transactions, the officer directly beneficially owned 23,600 shares of AMTM common stock.

How many restricted stock units remain outstanding for the Amentum (AMTM) officer?

After the vesting event on December 5, 2025, the officer held 5,444 restricted stock units, each representing a contingent right to receive one share of AMTM common stock.

What do the restricted stock units in this Amentum (AMTM) filing represent?

Each restricted stock unit represents a contingent right to receive one share of AMTM common stock, which is delivered when the units vest on specified dates.

Was this Amentum (AMTM) insider transaction an open-market stock purchase or sale?

No. The filing explains that the activity reflects distribution of AMTM common stock upon vesting of restricted stock units and shares tendered for tax withholding, not open-market trades.