Amentum Holdings, Inc. (formally Amentum Government Services Holding LLC) is an American government and commercial services contractor based in Chantilly, Virginia. The company was formed in 2020 from the spinout of Aecom's Management Services / federal group. After Leidos, it is the second-largest government services (non equipment producing) contractor in the US government contracting market.
Amentum was founded in 2020 as a spinout of the Management Services Group of Aecom, consisting of the non-construction parts of the company's federal work as well as its commercial operations and maintenance business. This came as a result of a process by AECOM to realign its business to focus more clearly on the architect, engineering, and construction market.
In March 2024, Amentum announced the completion of its merger with Jacobs Solutions.'s Critical Mission Solutions and Cyber and Intelligence businesses. In September of that year, it became a publicly traded company on the NYSE under the ticker symbol "AMTM", becoming a part of the S&P 500.
On April 23, 2025, Lockheed Martin announced it had agreed to buy Amentum's Rapid Business Solutions Business for $360M The deal was closed in June 2025.
As part of the strategy by its owners, Amentum has pursued acquisitions of other government contractors including: