Amentum (AMTM) CEO Heller vests 51,979 RSUs, withholds shares for tax

Rhea-AI Filing Summary

Amentum Holdings CEO John E. Heller reported stock activity tied to restricted stock units vesting. On January 28, 2026, 51,979 restricted stock units converted into an equal number of common shares. In connection with this vesting, 19,768 common shares were tendered to cover tax withholding at $35.71 per share.

After these transactions, Heller directly holds 366,058 shares of Amentum common stock and 103,959 restricted stock units, each representing a right to receive one share of common stock. The restricted stock units involved in this filing vested on January 28, 2026.

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

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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^*

Heller John E.

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
01/28/2026

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	01/28/2026		M		51,979	A	(1)	385,826	D
Common Stock	01/28/2026		F		19,768(2)	D	$35.71	366,058	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)	01/28/2026		M(1)			51,979	(4)	(4)	Common Stock	51,979	$0	103,959	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 January 28, 2026.

Remarks:

	/s/ Indira Lall	01/29/2026
	** 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).
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FAQ

What insider transaction did Amentum (AMTM) CEO John E. Heller report?

John E. Heller reported vesting of 51,979 restricted stock units, which converted into the same number of Amentum common shares. As part of this event, some shares were withheld to satisfy tax obligations tied to the RSU vesting.

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

The filing shows 19,768 Amentum common shares were tendered to cover tax withholding obligations at $35.71 per share. This withholding occurred in connection with the vesting and share distribution from previously granted restricted stock units.

How many Amentum (AMTM) shares does CEO John E. Heller own after this transaction?

Following the reported transactions, John E. Heller directly owns 366,058 Amentum common shares. In addition, he holds 103,959 restricted stock units, each representing a contingent right to receive one share of Amentum common stock in the future.

What are restricted stock units (RSUs) in the Amentum (AMTM) Form 4 filing?

In this filing, each restricted stock unit represents a contingent right to receive one share of Amentum common stock. When RSUs vest, they distribute common shares to the holder, as occurred with the 51,979 units that vested on January 28, 2026.

When did Amentum (AMTM) CEO John E. Heller’s RSUs vest?

The restricted stock units reported in the Form 4 vested on January 28, 2026. On that date, 51,979 RSUs converted into an equal number of Amentum common shares, triggering related tax withholding through the tender of some of those shares.

Is the Amentum (AMTM) CEO’s reported transaction a market sale of shares?

The filing characterizes the 19,768-share reduction as shares tendered for tax withholding upon RSU vesting. This indicates shares were withheld to cover taxes rather than described as an open-market sale to third-party buyers.