AMTM Amentum Holdings, Inc.
Amentum Holdings, Inc. (AMTM) Institutional Ownership
What the institutions did with AMTM last quarter, from their 13F filings. Counting managers rather than shares is the point: a single index fund adding to a position tells you far less than four hundred separate managers all deciding to. Positions as reported for the quarter ended September 30, 2026.
Every manager below opens. Subscribers can see any firm's whole portfolio — every position, its weight, and what they bought, trimmed and exited last quarter.
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Each block is one manager, sized by shares held and colored by how much they moved the position last quarter. Green added, red cut, grey stood pat.
Largest holders
| Manager | Shares | % of reported |
|---|---|---|
| DIMENSIONAL FUND ADVISORS LP | 7.2M | 25.3% |
| FMR LLC | 6.1M | 21.4% |
| THOMPSON SIEGEL & WALMSLEY LLC | 2.8M | 9.7% |
| GEODE CAPITAL MANAGEMENT, LLC | 2.6M | 9.1% |
| CACTI ASSET MANAGEMENT LLC | 875.1K | 3.1% |
| Bank of New York Mellon Corp | 835.5K | 2.9% |
| SEGRA CAPITAL MANAGEMENT, LLC | 774.9K | 2.7% |
| PRINCIPAL FINANCIAL GROUP INC | 730.8K | 2.6% |
| Pine Valley Investments Ltd Liability Co | 660.6K | 2.3% |
| ROYCE & ASSOCIATES LP | 585.2K | 2.1% |
| FIFTH THIRD BANCORP | 404.6K | 1.4% |
| Mawer Investment Management Ltd. | 365.4K | 1.3% |
| Russell Investments Group, Ltd. | 274.2K | 1.0% |
| EXCHANGE TRADED CONCEPTS, LLC | 273.2K | 1.0% |
| Nuveen, LLC | 270.3K | 0.9% |
| OpenArc Corporate Advisory, LLC | 175.5K | 0.6% |
| North Growth Management Ltd. | 175.0K | 0.6% |
| WEDGE CAPITAL MANAGEMENT L L P/NC | 168.7K | 0.6% |
| Telos Capital Management, Inc. | 166.9K | 0.6% |
| NEW YORK STATE TEACHERS RETIREMENT SYSTEM | 161.2K | 0.6% |
| Bryn Mawr Trust Advisors, LLC | 137.0K | 0.5% |
| BESSEMER GROUP INC | 129.5K | 0.5% |
| Mraz, Amerine & Associates, Inc. | 106.6K | 0.4% |
| Thrivent Financial for Lutherans | 98.6K | 0.3% |
| LPL Financial LLC | 93.9K | 0.3% |
Largest changes
| Manager | Action | Previous | Current | Change |
|---|---|---|---|---|
| Legacy Advisors, LLC | Sold Out | 9.1M | 0 | -9.1M |
| Thrivent Financial for Lutherans | Reduced | 2.1M | 98.6K | -2.0M |
| DIMENSIONAL FUND ADVISORS LP | Increased | 5.5M | 7.2M | +1.7M |
| SEGRA CAPITAL MANAGEMENT, LLC | Reduced | 2.0M | 774.9K | -1.3M |
| Pine Valley Investments Ltd Liability Co | Increased | 89.5K | 660.6K | +571.1K |
| Russell Investments Group, Ltd. | Reduced | 840.6K | 274.2K | -566.5K |
| THOMPSON SIEGEL & WALMSLEY LLC | Increased | 2.3M | 2.8M | +487.8K |
| FMR LLC | Increased | 5.7M | 6.1M | +435.7K |
| CenterBook Partners LP | Sold Out | 328.8K | 0 | -328.8K |
| Nuveen, LLC | Reduced | 421.5K | 270.3K | -151.2K |
| FIFTH THIRD BANCORP | Increased | 281.8K | 404.6K | +122.8K |
| GEODE CAPITAL MANAGEMENT, LLC | Reduced | 2.7M | 2.6M | -117.4K |
| OPPENHEIMER & CO INC | Reduced | 143.0K | 26.7K | -116.3K |
| ROYCE & ASSOCIATES LP | Reduced | 697.4K | 585.2K | -112.2K |
| BARCLAYS PLC | Reduced | 151.8K | 50.8K | -101.0K |
| Oak Thistle LLC | New | 0 | 87.8K | +87.8K |
| NATIXIS | Sold Out | 67.1K | 0 | -67.1K |
| DELPHI MANAGEMENT INC /MA/ | Sold Out | 55.5K | 0 | -55.5K |
| HAHN CAPITAL MANAGEMENT LLC | Sold Out | 49.7K | 0 | -49.7K |
| INTECH INVESTMENT MANAGEMENT LLC | Sold Out | 48.8K | 0 | -48.8K |
| Squarepoint Ops LLC | New | 0 | 47.5K | +47.5K |
| Carlson Capital, L.P. | New | 0 | 47.0K | +47.0K |
| Bank of New York Mellon Corp | Reduced | 878.1K | 835.5K | -42.6K |
| HARBOR CAPITAL ADVISORS, INC. | Increased | 39.5K | 80.3K | +40.7K |
| EXCHANGE TRADED CONCEPTS, LLC | Reduced | 305.3K | 273.2K | -32.1K |
| DBA TRADING, LLC | Sold Out | 31.2K | 0 | -31.2K |
| Lebenthal Global Advisors, LLC | Increased | 33.0K | 62.3K | +29.3K |
| State of Alaska, Department of Revenue | Reduced | 50.7K | 25.9K | -24.8K |
| Savant Capital, LLC | New | 0 | 24.3K | +24.3K |
| Amundi | New | 0 | 23.9K | +23.9K |
| WEDGE CAPITAL MANAGEMENT L L P/NC | Reduced | 187.8K | 168.7K | -19.1K |
| Telos Capital Management, Inc. | Reduced | 185.6K | 166.9K | -18.7K |
| Clear Harbor Asset Management, LLC | Reduced | 31.8K | 13.3K | -18.5K |
| Cambridge Investment Research Advisors, Inc. | Reduced | 33.0K | 15.8K | -17.1K |
| SIMPLEX TRADING, LLC | Sold Out | 17.0K | 0 | -17.0K |
| Mraz, Amerine & Associates, Inc. | Increased | 90.2K | 106.6K | +16.4K |
| Caitong International Asset Management Co., Ltd | Sold Out | 15.2K | 0 | -15.2K |
| QUADRANT CAPITAL GROUP LLC | Sold Out | 13.0K | 0 | -13.0K |
| Creative Planning | Increased | 54.4K | 67.1K | +12.7K |
| MQS Management LLC | New | 0 | 12.3K | +12.3K |
| Maryland State Retirement & Pension System | Increased | 29.8K | 41.6K | +11.7K |
| PRINCIPAL FINANCIAL GROUP INC | Reduced | 742.4K | 730.8K | -11.5K |
| Facet Wealth, Inc. | New | 0 | 11.4K | +11.4K |
| TOTH FINANCIAL ADVISORY CORP | Reduced | 18.2K | 7.0K | -11.2K |
| LECAP ASSET MANAGEMENT LTD | Sold Out | 10.4K | 0 | -10.4K |
| Universal- Beteiligungs- und Servicegesellschaft mbH | Increased | 33.8K | 43.9K | +10.0K |
| CITIGROUP INC | Increased | 31.5K | 40.5K | +9.0K |
| Sterling Capital Management LLC | Reduced | 13.4K | 4.5K | -8.9K |
| DEUTSCHE BANK AG\ | Increased | 21.8K | 29.0K | +7.2K |
| LEAVELL INVESTMENT MANAGEMENT, INC. | Increased | 24.7K | 31.8K | +7.1K |
| CACTI ASSET MANAGEMENT LLC | Reduced | 881.7K | 875.1K | -6.6K |
| Legal Advantage Investments, Inc. | Increased | 28.9K | 35.4K | +6.5K |
| Formidable Asset Management, LLC | Increased | 13.1K | 19.0K | +6.0K |
| WEALTH ENHANCEMENT ADVISORY SERVICES, LLC | Reduced | 76.5K | 71.0K | -5.5K |
| PNC Financial Services Group, Inc. | Increased | 12.0K | 17.5K | +5.5K |
| Crestwood Advisors Group, LLC | Reduced | 53.0K | 47.8K | -5.2K |
| OpenArc Corporate Advisory, LLC | Increased | 170.3K | 175.5K | +5.2K |
| Bryn Mawr Trust Advisors, LLC | Reduced | 141.4K | 137.0K | -4.4K |
| BANK OF MONTREAL /CAN/ | Increased | 20.5K | 24.7K | +4.2K |
| State of New Jersey Common Pension Fund D | Reduced | 61.0K | 56.9K | -4.1K |
13F filings are due 45 days after quarter end and cover long positions in U.S.-listed equities only, so this is a lagged and partial picture: shorts, bonds and foreign listings never appear. Options positions are excluded here rather than folded into the share counts. Political ownership is coming.