Christopher M.t. Thompson - 14 Aug 2026 Form 4 Insider Report for Amentum Holdings, Inc. (AMTM)

Reporting relationship: Director
Issuer ticker: AMTM
Reported as of: 14 Aug 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 17 Sep 2026, 21:35:55 UTC
Prior SEC filing: 10 Feb 2026
Source filing: View source filing
Reporting owner signature: /s/ Indira Lall, Attorney-in-fact

Key filing fact

Christopher M.t. Thompson filed Form 4 for Amentum Holdings, Inc. (AMTM) on 17 Sep 2026.

Key facts

This page summarizes Christopher M.t. Thompson's Form 4 filing for Amentum Holdings, Inc. (AMTM).
1 reported transaction and 0 derivative rows are listed below.
Accepted by SEC: 17 Sep 2026, 21:35.

Change

Previous filing in this sequence was filed on 10 Feb 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001483410 Primary reporting owner

Thompson Christopher M.T.

Relationship: Director
Address: C/O AMENTUM HOLDINGS, INC., 4800 WESTFIELDS BOULEVARD, SUITE 400, CHANTILLY
Signature: /s/ Indira Lall, Attorney-in-fact
Signature date: 17 Sep 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

AMTM transaction

Common Stock

Gift

Transaction value
Shares: -4,250
Change %: -42%
Price: $0.000000^*
Shares after: 5,750
Date: 14 Aug 2026
Ownership: By Trust
Footnotes: F1, F2

AMTM holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 5,062
Date: 14 Aug 2026
Ownership: Direct

AMTM holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 14,000
Date: 14 Aug 2026
Ownership: By Spouse

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 2 footnotes

Footnote F1

Mr. Thompson's filing was late due to an administrative oversight.

Footnote F2

On August 14, 2026, the reporting person transferred an LLC interest representing 4,250 shares of AMTM common stock to an immediate family for no consideration.