Amentum COO Arnette receives 12,702 vested shares

Q: How many AMTM shares did Stephen A. Arnette receive when his RSUs vested?

On November 6, 2026, 12,702 AMTM common shares were distributed upon vesting of his restricted stock units. Each restricted stock unit represents a contingent right to receive one common share.

Q: How many AMTM shares were tendered for tax withholding?

Stephen A. Arnette tendered 4,999 shares of AMTM common stock for tax withholding at $21.25 per share on November 6, 2026.

Tax withholding covered 4,999 common shares at $21.25 per share; the post-transaction derivative position was reported as 12,702 restricted stock units.

Available on EDGAR 11/10/2026 - 05:55 PM EST Accepted by SEC EDGAR 11/10/2026 - 05:54 PM EST

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Form Type

Rhea-AI Filing Summary

Amentum Holdings, Inc. Chief Operating Officer Stephen A. Arnette had 12,702 restricted stock units vest on November 6, 2026, with 12,702 common shares distributed. The derivative position was reported as 12,702 restricted stock units following the transaction. Arnette tendered 4,999 shares for tax withholding at $21.25 per share.

Insider Trade Summary

12,702 shares exercised/converted

Exercise 3 txns

Insider Arnette Stephen A

Role Chief Operating Officer

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units ^{F3, F4}	12,702	$0.00	$0.00
Exercise	Common Stock ^F1	12,702	--	--
Tax Withholding	Common Stock ^F2	4,999	$21.25	$106K

Holdings After Transaction: Restricted Stock Units — 12,702 units (Direct); Common Stock — 114,355 shares (Direct)

Holdings Before and After: Restricted Stock Units, 25,404 to 12,702 units (Direct); Common Stock, 106,652 to 114,355 shares (Direct)

Footnotes (4)

F1. Represents distribution of AMTM common stock upon vesting of restricted stock units.
F2. Represents number of shares of AMTM common stock tendered for tax withholding upon vesting of restricted stock units.
F3. Each restricted stock unit represents a contingent right to receive one share of AMTM common stock.
F4. One-third of the restricted stock units shall vest and be delivered, net of tax withholding, on each of the first, second and third anniversaries of the date of grant.

Key Figures

Common shares distributed: 12,702 shares Shares tendered for tax withholding: 4,999 shares Tax-withholding price: $21.25 per share +1 more

4 metrics

Common shares distributed 12,702 shares Upon vesting on November 6, 2026

Shares tendered for tax withholding 4,999 shares On November 6, 2026

Tax-withholding price $21.25 per share On November 6, 2026

Restricted stock units following transaction 12,702 units Reported following the November 6, 2026 transaction

Key Terms

Restricted Stock Units, contingent right, tax withholding

3 terms

Restricted Stock Units financial

"distribution of AMTM common stock upon vesting of restricted stock units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

contingent right financial

"Each restricted stock unit represents a contingent right to receive one share"

tax withholding financial

"shares of AMTM common stock tendered for tax withholding upon vesting"

Tax withholding is the practice of taking a portion of a payment—such as wages, dividends, or sale proceeds—before it reaches the recipient and sending that portion to the tax authority as an advance on the recipient’s eventual tax bill. For investors it matters because withholding reduces immediate cash received and affects after‑tax returns, estimated tax payments, and whether you may owe more or receive a refund when taxes are finally calculated, like having a small automatic savings set aside for your tax bill.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many AMTM shares did Stephen A. Arnette receive when his RSUs vested?

On November 6, 2026, 12,702 AMTM common shares were distributed upon vesting of his restricted stock units. Each restricted stock unit represents a contingent right to receive one common share.

How many AMTM shares were tendered for tax withholding?

Stephen A. Arnette tendered 4,999 shares of AMTM common stock for tax withholding at $21.25 per share on November 6, 2026.

What are the vesting terms for Arnette's restricted stock units?

One-third of the restricted stock units shall vest and be delivered, net of tax withholding, on each of the first, second and third anniversaries of the grant date.

AI-generated analysis. How Rhea-AI works. Not financial advice.

Form 4 Insider Transactions: What Each Field Means →

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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
Estimated average burden
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^*

Arnette Stephen A

(Last)

(First)

(Middle)

C/O AMENTUM HOLDINGS, INC.

4800 WESTFIELDS BOULEVARD, SUITE 400

(Street)

CHANTILLY

VIRGINIA

20151

(City)

(State)

(Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
11/06/2026

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

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

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

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	11/06/2026		M		12,702	A	⁽¹⁾	119,354	D
Common Stock	11/06/2026		F		4,999⁽²⁾	D	$21.25	114,355	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Restricted Stock Units	⁽³⁾	11/06/2026		M			12,702	⁽⁴⁾	⁽⁴⁾	Common Stock	12,702	$0	12,702	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. One-third of the restricted stock units shall vest and be delivered, net of tax withholding, on each of the first, second and third anniversaries of the date of grant.

Remarks:

	/s/ Indira Lall, Attorney-in-Fact	11/10/2026
	** 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).
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.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR