Amentum Holdings, Inc. (AMTM) Institutional OwnershipQ2 2026 13F Data|Updated 2026-11-07
Institutional ownership increased this quarter (+2.51 pp), though top 10 holders maintain a highly concentrated 65.6% of institutional value.
Ranked by reported Q2 2026 13F market value
Share of total reported institutional value in AMTM held by the largest 10 / 25 filers.
| # | Institution | Shares Held | Market Value | QoQ Change | Ownership % | % of Fund |
|---|---|---|---|---|---|---|
| 1 | AMERICAN SECURITIES LLC | 45.0M | $930.7M | 0.0% | 18.447% | 24.79% |
| 2 | Invesco Ltd. | 25.0M | $515.8M | +16.2% | 10.223% | 0.04% |
| 3 | BlackRock, Inc. | 17.9M | $370.1M | +0.4% | 7.336% | 0.01% |
| 4 | PRIMECAP MANAGEMENT CO/CA/ | 12.3M | $253.9M | +1.7% | 5.033% | 0.15% |
| 5 | VANGUARD PORTFOLIO MANAGEMENT LLC | 7.9M | $164.3M | +1.2% | 3.256% | 0.01% |
| 6 | VANGUARD CAPITAL MANAGEMENT LLC | 6.7M | $138.7M | +0.9% | 2.750% | 0.00% |
| 7 | FMR LLC | 5.7M | $117.4M | +1.8% | 2.327% | 0.01% |
| 8 | DIMENSIONAL FUND ADVISORS LP | 5.5M | $114.5M | +46.2% | 2.269% | 0.02% |
| 9 | STATE STREET CORP | 5.2M | $106.5M | +1.4% | 2.111% | 0.00% |
| 10 | FRONTIER CAPITAL MANAGEMENT CO LLC | 4.1M | $85.7M | -16.0% | 1.698% | 0.80% |
| 11 | Troluce Capital Advisors LLC | 3.6M | $73.7M | +256.5% | 1.461% | 7.59% |
| 12 | GEODE CAPITAL MANAGEMENT, LLC | 2.7M | $56.2M | -3.5% | 1.113% | 0.00% |
| 13 | GOLDMAN SACHS GROUP INC | 2.7M | $56.1M | +139.7% | 1.111% | 0.00% |
| 14 | MORGAN STANLEY | 2.7M | $55.0M | +19.1% | 1.091% | 0.00% |
| 15 | MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. | 2.3M | $47.9M | -16.8% | 0.950% | 0.06% |
| 16 | SEGRA CAPITAL MANAGEMENT, LLC | 2.2M | $46.3M | +23.4% | 0.917% | 9.33% |
| 17 | MILLENNIUM MANAGEMENT LLC | 2.1M | $44.0M | +237.2% | 0.872% | 0.02% |
| 18 | CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 2.1M | $43.8M | +2.5% | 0.869% | 0.01% |
| 19 | BANK OF AMERICA CORP /DE/ | 2.0M | $42.2M | -15.1% | 0.837% | 0.00% |
| 20 | Verition Fund Management LLC | 2.0M | $41.7M | +55.6% | 0.827% | 0.11% |
| 21 | VAN ECK ASSOCIATES CORP | 2.0M | $41.1M | +263.2% | 0.815% | 0.03% |
| 22 | VOYA INVESTMENT MANAGEMENT LLC | 2.0M | $40.8M | +64.6% | 0.809% | 0.04% |
| 23 | UBS Group AG | 1.5M | $31.9M | -9.7% | 0.633% | 0.00% |
| 24 | NORGES BANK | 1.5M | $31.3M | — | 0.621% | 0.00% |
| 25 | Permian Investment Partners, LP | 1.4M | $29.6M | -8.6% | 0.587% | 3.25% |
denotes a marquee investor (Buffett, Burry, ARK, Tiger Global, Pershing Square, Baupost and other widely-followed managers). “% of Fund” shows how much of that investor’s total 13F portfolio is invested in AMTM — a direct measure of their conviction.
Filings activity in AMTM during Q2 2026, grouped by how each filer changed its position.
Institutions that opened a new AMTM position in Q2 2026
Institutions that fully closed their AMTM position in Q2 2026
8 quarters of 13F filings · Δ columns show change vs prior quarter
| Quarter | Inst. Holders | Δ Holders | Ownership % | Δ Ownership | Total 13F Value | Δ Value |
|---|---|---|---|---|---|---|
| Q2 2026 | 462 | 4.5% | 90.88% | +2.51 pp | $4.26B | 18% |
| Q1 2026 | 484 | +0.6% | 88.37% | +3.03 pp | $5.22B | 7.5% |
| Q4 2025 | 481 | +6.9% | 85.34% | +4.92 pp | $5.65B | +25% |
| Q3 2025 | 450 | 1.7% | 80.42% | 0.70 pp | $4.50B | +1.1% |
| Q2 2025 | 458 | +13% | 81.12% | +4.51 pp | $4.45B | +40% |
| Q1 2025 | 405 | 7.3% | 76.61% | +20.74 pp | $3.18B | +21% |
| Q4 2024 | 437 | 8.2% | 55.87% | +14.92 pp | $2.62B | 14% |
| Q3 2024 | 476 | — | 40.95% | — | $3.05B | — |
Source: SEC 13F institutional filings. Ownership % requires market cap data and will show once linked. Δ columns compare to the immediately prior filed quarter.
Quick answers to the most common questions about buying AMTM stock.
Based on Q2 2026 13F filings, institutional ownership of Amentum Holdings, Inc. stands at 90.9%, held across 462 reporting institutions.
AMERICAN SECURITIES LLC is the largest reported institutional holder of AMTM, with approximately 45,026,743 shares worth $0.93B as of Q2 2026.
Yes — 1 widely-followed marquee investor appear among the top 25 institutional holders of AMTM, including MILLENNIUM MANAGEMENT LLC.
Our composite Smart Money Score for AMTM is 52 out of 100 (Neutral). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
50 institutions opened new positions in AMTM during Q2 2026, while 72 fully exited. 69 added to existing positions and 329 trimmed.
AMTM institutional ownership rose by 2.51 percentage points quarter-over-quarter, with a net change of -22 holders.
The top 10 institutions account for 65.6% of all reported 13F value in AMTM, and the top 25 account for 81.6%.
All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.