Amentum Holdings, Inc. (AMTM) ownership: Top institutional holder: AMERICAN SECURITIES LLC ($1.17B). Insider activity: Net Seller (5 buys, 15 sells). 2 recent congressional STOCK Act disclosures. SEC EDGAR first-party data.
| Holder | Shares | Market Value | Reported |
|---|---|---|---|
| AMERICAN SECURITIES LLC | 45026743.00 | $1.17B | 2026-03-31 |
| Invesco Ltd. | 21473778.00 | $560.04M | 2026-03-31 |
| BlackRock, Inc. | 17841283.00 | $465.30M | 2026-03-31 |
| VANGUARD GROUP INC | 15411745.00 | $446.94M | 2025-12-31 |
| PRIMECAP MANAGEMENT CO/CA/ | 12085294.00 | $315.18M | 2026-03-31 |
| VANGUARD PORTFOLIO MANAGEMENT LLC | 7852951.00 | $204.80M | 2026-03-31 |
| VANGUARD CAPITAL MANAGEMENT LLC | 6650879.00 | $173.45M | 2026-03-31 |
| FMR LLC | 5578386.00 | $145.48M | 2026-03-31 |
| Insider | Transaction | Value | Date |
|---|---|---|---|
| Sell | null | 2026-05-06 | |
| Sell | null | 2026-05-06 | |
| Sell | null | 2026-05-06 | |
| Sell | null | 2026-05-06 | |
| Sell | null | 2026-05-06 | |
| Sell | null | 2026-05-06 | |
| Buy | null | 2026-05-06 | |
| Buy | null | 2026-05-06 |
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Institutional data from SEC Form 13F. Insider data from SEC Form 4. Congressional data from STOCK Act disclosures. Not personalized investment advice.