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

Rhea-AI Filing Summary

Amentum Holdings, Inc. (AMTM) reported insider equity activity by its Chief Operating Officer on a Form 4. On November 15 and 16, 2025, restricted stock units (RSUs) vested, resulting in multiple conversions of RSUs into AMTM common stock, reported with transaction code M. The COO received common shares in amounts including 5,758, 5,053, 3,681, and 4,596 shares as RSUs vested and were distributed as stock. To cover tax withholding upon these vestings, the officer surrendered AMTM common shares in separate transactions with code F, including 1,403, 1,231, and 1,120 shares at a price of $22.07 per share. Following the reported transactions, the COO beneficially owned 46,065 shares of AMTM common stock directly and continued to hold RSUs with contingent rights to receive additional shares.

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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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^*

Arnette Stephen A

(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 Operating Officer

3. Date of Earliest Transaction (Month/Day/Year)
11/15/2025

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	11/15/2025		M		5,758	A	(1)	37,386	D
Common Stock	11/15/2025		F		1,403(2)	D	$22.07	35,983	D
Common Stock	11/16/2025		M		5,053	A	(1)	41,036	D
Common Stock	11/16/2025		F		1,231(2)	D	$22.07	39,805	D
Common Stock	11/16/2025		M		3,681	A	(1)	43,486	D
Common Stock	11/16/2025		F		897(2)	D	$22.07	42,589	D
Common Stock	11/16/2025		M		4,596	A	(1)	47,185	D
Common Stock	11/16/2025		F		1,120(2)	D	$22.07	46,065	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)	11/15/2025		M(1)			5,758	(4)	(4)	Common Stock	5,758	$0	11,515	D
Restricted Stock Units	(3)	11/16/2025		M(1)			5,053	(5)	(5)	Common Stock	5,053	$0	5,053	D
Restricted Stock Units	(3)	11/16/2025		M(1)			3,681	(5)	(5)	Common Stock	3,681	$0	0	D
Restricted Stock Units	(3)	11/16/2025		M(1)			4,596	(5)	(5)	Common Stock	4,596	$0	0	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 15, 2025.

5. The restricted stock units awarded vested on November 16, 2025.

Remarks:

	/s/ Mark Esposito, Attorney-in-Fact	11/18/2025
	** 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 transactions did Amentum (AMTM) report for its COO?

The Chief Operating Officer of Amentum Holdings, Inc. (AMTM) reported the vesting of restricted stock units and related share issuances of AMTM common stock on November 15 and 16, 2025, along with share withholdings to satisfy tax obligations.

How many Amentum (AMTM) shares did the COO acquire through RSU vesting?

Through RSU vesting, the COO acquired AMTM common stock in several transactions, including 5,758, 5,053, 3,681, and 4,596 shares, as RSUs converted into common stock.

How many Amentum (AMTM) shares were withheld for taxes in these Form 4 transactions?

To cover tax withholding upon RSU vesting, the COO tendered AMTM shares in transactions coded F, including 1,403, 1,231, and 1,120 shares at a price of $22.07 per share.

What is the COO’s AMTM common stock ownership after the reported transactions?

After the reported RSU vesting and tax-withholding transactions, the COO beneficially owned 46,065 shares of AMTM common stock directly.

What do the reported Amentum (AMTM) restricted stock units represent?

Each reported restricted stock unit represents a contingent right to receive one share of AMTM common stock. The filing notes that RSU awards vested on November 15, 2025 and November 16, 2025.

What do Form 4 transaction codes M and F mean in the AMTM filing?

In the AMTM Form 4, code M indicates the conversion of restricted stock units into common stock upon vesting, and code F indicates shares of common stock tendered to satisfy tax withholding obligations related to that vesting.