Amentum Holdings, Inc. - Director's Dealing 2025

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Amentum Holdings, Inc. (AMTM)
CIK: 0002011286
Period of Report: 2025-11-17

Reporting Person: Arnette Stephen A (Chief Operating Officer)

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2025-11-17	Common Stock	M	1178	—	Acquired	47243	Direct
2025-11-17	Common Stock	F	287	$21.49	Disposed	46956	Direct
2025-11-17	Common Stock	A	46769	—	Acquired	93725	Direct

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2025-11-17	Restricted Stock Units	$	M	1178	Disposed		Common Stock (1178)	Direct

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: One-third of the restricted stock units shall vest on each of the first, second and third anniversaries of November 17, 2025.

F4: Each restricted stock unit represents a contingent right to receive one share of AMTM common stock.

F5: The restricted stock units awarded vested on November 17, 2025.