Amentum (AMTM) S-8Registration of securities for employees

Amentum Holdings, Inc. (the “Company”) previously filed a Registration Statement on Form S-8 (the “Prior Registration Statement”) with the Securities and Exchange Commission (the “Commission”) on October 4, 2024 (File No. 333-282510), which is hereby incorporated by reference.

This Registration Statement on Form S-8 (this “Registration Statement”) is filed by the Company to register the following shares of its common stock, par value $0.01 per share (“Common Stock”), as previously approved by the Company’s sole stockholder: (i) 1,311,589 shares of Common Stock issuable to eligible recipients under the Amentum Holdings, Inc. 2024 Stock Incentive Plan; and (ii) 211,567 shares of Common Stock issuable to eligible recipients under the Amentum Holdings, Inc. Employee Stock Purchase Plan.

Pursuant to General Instruction E to Form S-8, the contents of the Prior Registration Statement are incorporated by reference into this Registration Statement, except to the extent supplemented, amended or superseded by the information set forth herein.

Pursuant to the requirements of the Securities Act of 1933 (the “Securities Act”), the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in Chantilly, Commonwealth of Virginia, on this 8th day of November, 2024.

Each of the undersigned officers and directors of Amentum Holdings, Inc. hereby severally constitutes and appoints Travis B. Johnson and Paul W. Cobb, Jr. and each of them acting alone, as such person’s true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for such person and in such person’s name, place and stead, and in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement and to file the same, with all exhibits thereto and other documents in connection therewith, with the Commission and any applicable securities exchange or securities self-regulatory body, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as such person might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or either of them individually, or their or such person’s substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.