Who owns Amentum Holdings (AMTM)
Which tracked institutional funds hold AMTM, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See AMTM company fundamentals →
Ownership as of the 2026-Q2 13F filings (latest filed 2026-09-22). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
49 tracked funds added or opened AMTM while 133 trimmed or exited it between 2026-Q1 and 2026-Q2 — the tape is split. When large holders disagree on a name, the funds moving first are sometimes ahead of the story.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
AMTM’s largest tracked holder by dollar value, AMERICAN SECURITIES LLC, sizes it at 24.8% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 24.8pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in AMTM divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2026-Q1 and 2026-Q2, across 429 tracked filers holding AMTM, 196 increased or opened the position and 258 reduced or closed it; over the same quarter, there were no open-market insider Form 4s.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in AMTM between the 2026-Q1 and 2026-Q2 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
New buyers 16
- Loews Corp$10M
- SHAPIRO CAPITAL MANAGEMENT LLC$10M
- ExodusPoint Capital Management, LP$5M
- Verbena Value LP$4M
- TWINBEECH CAPITAL LP$2M
- Cascade Investment Advisors, Inc.$1M
Full exits 38
- Thrivent Financial for Lutherans$55M
- TORONTO DOMINION BANK$41M
- THOMPSON SIEGEL & WALMSLEY LLC$40M
- BRIGHTLINE CAPITAL MANAGEMENT, LLC$36M
- COOPER CREEK PARTNERS MANAGEMENT LLC$24M
- Penn Capital Management Company, LLC$18M
Largest adds
- Troluce Capital Advisors LLC$48M
- BlackRock, Inc.$41M
- MILLENNIUM MANAGEMENT LLC$28M
- VAN ECK ASSOCIATES CORP$27M
- GOLDMAN SACHS GROUP INC$27M
- Qube Research & Technologies Ltd$19M
Largest trims
- AMERICAN SECURITIES LLC$244M
- Focus Partners Wealth$65M
- PRIMECAP MANAGEMENT CO/CA/$61M
- Arvin Capital Management LP$45M
- FRONTIER CAPITAL MANAGEMENT CO LLC$43M
- VANGUARD PORTFOLIO MANAGEMENT LLC$41M
Institutional holders
One row per tracked fund, most shares held first (every row is from one quarter; reported value breaks ties). “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding.
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| AMERICAN SECURITIES LLC | 45,026,743 | $931M | 22.8% | 2026-Q2 |
| Invesco Ltd. added | 24,954,251 | $516M | 12.6% | 2026-Q2 |
| BlackRock, Inc. added | 17,906,984 | $370M | 9.1% | 2026-Q2 |
| PRIMECAP MANAGEMENT CO/CA/ added | 12,285,504 | $254M | 6.2% | 2026-Q2 |
| Legacy Advisors, LLC added | 9,065,677 | $9M | 0.2% | 2026-Q2 |
| VANGUARD PORTFOLIO MANAGEMENT LLC added | 7,948,385 | $164M | 4.0% | 2026-Q2 |
| VANGUARD CAPITAL MANAGEMENT LLC added | 6,711,987 | $139M | 3.4% | 2026-Q2 |
| FMR LLC added | 5,679,175 | $117M | 2.9% | 2026-Q2 |
| DIMENSIONAL FUND ADVISORS LP added | 5,537,696 | $114M | 2.8% | 2026-Q2 |
| STATE STREET CORP added | 5,151,772 | $106M | 2.6% | 2026-Q2 |
| FRONTIER CAPITAL MANAGEMENT CO LLC trimmed | 4,143,971 | $86M | 2.1% | 2026-Q2 |
| Troluce Capital Advisors LLC added | 3,565,399 | $74M | 1.8% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC trimmed | 2,716,560 | $56M | 1.4% | 2026-Q2 |
| GOLDMAN SACHS GROUP INC added | 2,711,866 | $56M | 1.4% | 2026-Q2 |
| MORGAN STANLEY added | 2,662,329 | $55M | 1.3% | 2026-Q2 |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. trimmed | 2,318,581 | $48M | 1.2% | 2026-Q2 |
| MILLENNIUM MANAGEMENT LLC added | 2,127,779 | $44M | 1.1% | 2026-Q2 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC added | 2,120,102 | $44M | 1.1% | 2026-Q2 |
| BANK OF AMERICA CORP /DE/ trimmed | 2,042,897 | $42M | 1.0% | 2026-Q2 |
| SEGRA CAPITAL MANAGEMENT, LLC added | 2,037,890 | $42M | 1.0% | 2026-Q2 |
| Verition Fund Management LLC added | 2,019,334 | $42M | 1.0% | 2026-Q2 |
| VAN ECK ASSOCIATES CORP added | 1,988,898 | $41M | 1.0% | 2026-Q2 |
| VOYA INVESTMENT MANAGEMENT LLC added | 1,974,191 | $41M | 1.0% | 2026-Q2 |
| UBS Group AG trimmed | 1,545,183 | $32M | 0.8% | 2026-Q2 |
| NORGES BANK trimmed | 1,516,193 | $31M | 0.8% | 2026-Q2 |
| Permian Investment Partners, LP trimmed | 1,433,028 | $30M | 0.7% | 2026-Q2 |
| 683 Capital Management, LLC added | 1,100,000 | $23M | 0.6% | 2026-Q2 |
| LOOMIS SAYLES & CO L P trimmed | 1,042,522 | $22M | 0.5% | 2026-Q2 |
| Qube Research & Technologies Ltd added | 1,034,395 | $21M | 0.5% | 2026-Q2 |
| NORTHERN TRUST CORP added | 1,029,892 | $21M | 0.5% | 2026-Q2 |
| VANGUARD FIDUCIARY TRUST CO added | 968,451 | $20M | 0.5% | 2026-Q2 |
| CACTI ASSET MANAGEMENT LLC | 881,692 | $18M | 0.4% | 2026-Q2 |
| Bank of New York Mellon Corp trimmed | 878,084 | $18M | 0.4% | 2026-Q2 |
| Russell Investments Group, Ltd. added | 840,642 | $17M | 0.4% | 2026-Q2 |
| AVENIR CORP trimmed | 811,726 | $17M | 0.4% | 2026-Q2 |
| WELLS FARGO & COMPANY/MN added | 750,214 | $16M | 0.4% | 2026-Q2 |
| PRINCIPAL FINANCIAL GROUP INC trimmed | 742,381 | $15M | 0.4% | 2026-Q2 |
| Ancora Advisors LLC added | 715,652 | $15M | 0.4% | 2026-Q2 |
| ROYCE & ASSOCIATES LP added | 697,368 | $14M | 0.4% | 2026-Q2 |
| CITADEL ADVISORS LLC added | 670,684 | $14M | 0.3% | 2026-Q2 |
| Point72 Asset Management, L.P. trimmed | 649,984 | $13M | 0.3% | 2026-Q2 |
| AQR CAPITAL MANAGEMENT LLC added | 601,900 | $12M | 0.3% | 2026-Q2 |
| FIRST TRUST ADVISORS LP added | 547,907 | $11M | 0.3% | 2026-Q2 |
| Ruane, Cunniff & Goldfarb L.P. trimmed | 537,213 | $11M | 0.3% | 2026-Q2 |
| Public Sector Pension Investment Board trimmed | 528,821 | $11M | 0.3% | 2026-Q2 |
| Loews Corp added | 500,000 | $10M | 0.3% | 2026-Q2 |
| FIRST NATIONAL BANK OF OMAHA added | 475,992 | $10M | 0.2% | 2026-Q2 |
| SHAPIRO CAPITAL MANAGEMENT LLC new | 475,970 | $10M | 0.2% | 2026-Q2 |
| Nuveen, LLC trimmed | 421,495 | $9M | 0.2% | 2026-Q2 |
| Arvin Capital Management LP trimmed | 416,705 | $9M | 0.2% | 2026-Q2 |
| HOTCHKIS & WILEY CAPITAL MANAGEMENT LLC added | 402,130 | $8M | 0.2% | 2026-Q2 |
| SUSQUEHANNA FUNDAMENTAL INVESTMENTS, LLC added | 394,370 | $8M | 0.2% | 2026-Q2 |
| BOOTHBAY FUND MANAGEMENT, LLC added | 387,973 | $8M | 0.2% | 2026-Q2 |
| De Lisle Partners LLP trimmed | 374,818 | $8M | 0.2% | 2026-Q2 |
| Vident Advisory, LLC trimmed | 372,918 | $8M | 0.2% | 2026-Q2 |
| Mawer Investment Management Ltd. added | 369,557 | $8M | 0.2% | 2026-Q2 |
| MOORE CAPITAL MANAGEMENT, LP trimmed | 365,096 | $8M | 0.2% | 2026-Q2 |
| Legal & General Group Plc added | 349,048 | $7M | 0.2% | 2026-Q2 |
| JANE STREET GROUP, LLC added | 343,687 | $7M | 0.2% | 2026-Q2 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP added | 332,452 | $7M | 0.2% | 2026-Q2 |
| CenterBook Partners LP added | 328,766 | $7M | 0.2% | 2026-Q2 |
| AMERIPRISE FINANCIAL INC trimmed | 319,479 | $7M | 0.2% | 2026-Q2 |
| GRIZZLYROCK CAPITAL, LLC added | 318,363 | $7M | 0.2% | 2026-Q2 |
| Swiss National Bank added | 318,091 | $7M | 0.2% | 2026-Q2 |
| Rovida Investment Management Ltd | 315,000 | $7M | 0.2% | 2026-Q2 |
| Aristotle Capital Boston, LLC trimmed | 307,836 | $6M | 0.2% | 2026-Q2 |
| EXCHANGE TRADED CONCEPTS, LLC added | 305,286 | $6M | 0.2% | 2026-Q2 |
| TWO SIGMA INVESTMENTS, LP trimmed | 284,268 | $6M | 0.1% | 2026-Q2 |
| RHUMBLINE ADVISERS trimmed | 284,060 | $6M | 0.1% | 2026-Q2 |
| FIFTH THIRD BANCORP added | 281,815 | $6M | 0.1% | 2026-Q2 |
| California Public Employees Retirement System trimmed | 266,383 | $6M | 0.1% | 2026-Q2 |
| Hudson Value Partners, LLC added | 250,185 | $5M | 0.1% | 2026-Q2 |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC added | 249,725 | $5M | 0.1% | 2026-Q2 |
| AWH Capital, L.P. | 235,250 | $5M | 0.1% | 2026-Q2 |
| ExodusPoint Capital Management, LP trimmed | 226,289 | $5M | 0.1% | 2026-Q2 |
| RAYMOND JAMES FINANCIAL INC trimmed | 224,399 | $5M | 0.1% | 2026-Q2 |
| Hel Ved Capital Management Ltd added | 214,000 | $4M | 0.1% | 2026-Q2 |
| D. E. Shaw & Co., Inc. added | 191,488 | $4M | 0.1% | 2026-Q2 |
| SEI INVESTMENTS CO trimmed | 190,069 | $4M | 0.1% | 2026-Q2 |
| WEDGE CAPITAL MANAGEMENT L L P/NC added | 187,832 | $4M | 0.1% | 2026-Q2 |
| Verbena Value LP new | 186,200 | $4M | 0.1% | 2026-Q2 |
| Telos Capital Management, Inc. trimmed | 185,611 | $4M | 0.1% | 2026-Q2 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM trimmed | 183,223 | $4M | 0.1% | 2026-Q2 |
| OpenArc Corporate Advisory, LLC trimmed | 170,291 | $4M | 0.1% | 2026-Q2 |
| Brevan Howard Capital Management LP added | 167,354 | $3M | 0.1% | 2026-Q2 |
| Atom Investors LP added | 160,876 | $3M | 0.1% | 2026-Q2 |
| Gotham Asset Management, LLC trimmed | 156,113 | $3M | 0.1% | 2026-Q2 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 152,081 | $3M | 0.1% | 2026-Q2 |
| BARCLAYS PLC added | 151,780 | $3M | 0.1% | 2026-Q2 |
| Soviero Asset Management, LP trimmed | 150,000 | $3M | 0.1% | 2026-Q2 |
| OPPENHEIMER & CO INC trimmed | 142,974 | $3M | 0.1% | 2026-Q2 |
| Bryn Mawr Trust Advisors, LLC added | 141,443 | $3M | 0.1% | 2026-Q2 |
| PRUDENTIAL FINANCIAL INC trimmed | 139,950 | $3M | 0.1% | 2026-Q2 |
| Focus Partners Wealth trimmed | 138,344 | $3M | 0.1% | 2026-Q2 |
| Vanguard Global Advisers, LLC added | 137,394 | $3M | 0.1% | 2026-Q2 |
| VANGUARD ASSET MANAGEMENT, Ltd | 127,793 | $3M | 0.1% | 2026-Q2 |
| JPMORGAN CHASE & CO added | 119,174 | $3M | 0.1% | 2026-Q2 |
| SOROS FUND MANAGEMENT LLC added | 118,276 | $2M | 0.1% | 2026-Q2 |
| STATE BOARD OF ADMINISTRATION OF FLORIDA RETIREMENT SYSTEM trimmed | 117,135 | $2M | 0.1% | 2026-Q2 |
| ALGERT GLOBAL LLC added | 102,220 | $2M | 0.1% | 2026-Q2 |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.