Basis of Presentation	9 Months Ended
Jul. 03, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation Amentum Holdings, Inc. (collectively with its subsidiaries, “we,” “us,” “our,” “Amentum,” or the “Company”) is a global advanced engineering and technology solutions provider to a broad base of U.S. and allied government agencies, and customers in international and commercial markets, supporting programs of critical national importance across energy and environmental, intelligence, space, defense, civilian and commercial end-markets. We offer a broad reach of capabilities including energy, environmental remediation, intelligence and counter threat solutions, data fusion and analytics, engineering and integration, advanced test, training and readiness, and citizen solutions. As a leading provider of differentiated technology solutions, we have built a repertoire of deep customer knowledge, enabling us to engage our customers across multiple capabilities and markets. We conduct our business activities and report financial results as two reportable segments: Digital Solutions (“DS”) and Global Engineering Solutions (“GES”). The DS segment provides advanced digital and data-driven solutions including intelligence analytics, space system development, cybersecurity, and next generation IT across the federal government and commercial clients. The GES segment provides large-scale environmental remediation, nuclear power solutions, platform engineering, sustainment and supply chain management across all seven continents for the U.S. government and allied nations. The accompanying unaudited condensed consolidated financial statements of the Company include the assets, liabilities, results of operations, comprehensive income and cash flows for the Company, including its wholly-owned subsidiaries and joint ventures that are majority-owned or otherwise controlled by the Company. Certain information and note disclosures normally included in the annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted, although the Company believes that the disclosures made are adequate to make the information presented not misleading. All intercompany transactions and balances have been eliminated in consolidation. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments and reclassifications (all of which are of a normal, recurring nature) that are necessary for the fair presentation of the periods presented. It is suggested that these unaudited condensed consolidated financial statements be read in conjunction with the audited consolidated financial statements and the notes thereto included in the Company’s latest annual report for the fiscal year ended October 3, 2025. The results of operations for the three and nine months ended July 3, 2026 are not necessarily indicative of the results to be expected for any subsequent interim period or for the full fiscal year.

Amentum Holdings, Inc. (collectively with its subsidiaries, “we,” “us,” “our,” “Amentum,” or the “Company”) is a global advanced engineering and technology solutions provider to a broad base of U.S. and allied government agencies, and customers in international and commercial markets, supporting programs of critical national importance across energy and environmental, intelligence, space, defense, civilian and commercial end-markets. We offer a broad reach of capabilities including energy, environmental remediation, intelligence and counter threat solutions, data fusion and analytics, engineering and integration, advanced test, training and readiness, and citizen solutions. As a leading provider of differentiated technology solutions, we have built a repertoire of deep customer knowledge, enabling us to engage our customers across multiple capabilities and markets.

We conduct our business activities and report financial results as two reportable segments: Digital Solutions (“DS”) and Global Engineering Solutions (“GES”). The DS segment provides advanced digital and data-driven solutions including intelligence analytics, space system development, cybersecurity, and next generation IT across the federal government and commercial clients. The GES segment provides large-scale environmental remediation, nuclear power solutions, platform engineering, sustainment and supply chain management across all seven continents for the U.S. government and allied nations.

The accompanying unaudited condensed consolidated financial statements of the Company include the assets, liabilities, results of operations, comprehensive income and cash flows for the Company, including its wholly-owned subsidiaries and joint ventures that are majority-owned or otherwise controlled by the Company. Certain information and note disclosures normally included in the annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted, although the Company believes that the disclosures made are adequate to make the information presented not misleading. All intercompany transactions and balances have been eliminated in consolidation.

In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments and reclassifications (all of which are of a normal, recurring nature) that are necessary for the fair presentation of the periods presented. It is suggested that these unaudited condensed consolidated financial statements be read in conjunction with the audited consolidated financial statements and the notes thereto included in the Company’s latest annual report for the fiscal year ended October 3, 2025. The results of operations for the three and nine months ended July 3, 2026 are not necessarily indicative of the results to be expected for any subsequent interim period or for the full fiscal year.