Companies / Amentum Holdings, Inc.
Amentum Holdings, Inc.
NYSE: AMTMCIK 2011286CHANTILLY, VA
Financials · FY2025
Ownership
244.5M shares outstanding · as of Aug 7, 2026
Ownership
| Insiders | 0.50% | 1,229,187 |
| Institutions | 83.73% | 204,731,269 |
| Public float | 15.76% | 38,545,957 |
% of common shares outstanding (exact, from the latest cover-page filing). Institutions are quarterly 13F snapshots; insiders reflect current officers & directors.
Insiders 12
View all →| Insider | % of shares | Shares |
|---|---|---|
Vollmer John C.Director | 0.18% | 429,842 |
Heller John E.CEOChief Executive Officer · Director | 0.15% | 366,058 |
Bruning Jill LChief Technology Officer | 0.08% | 190,999 |
Arnette Stephen AChief Operating Officer | 0.04% | 96,357 |
Eberhart Ralph EDirector | 0.02% | 48,120 |
Brooks Vincent KDirector | 0.01% | 27,462 |
St. Mary Michele TChief Legal Officer & GC | 0.01% | 27,043 |
Rowland Sandra E.Director | <0.01% | 20,073 |
Loughran BarbaraDirector | <0.01% | 9,662 |
Ireland Susan LeslieDirector | <0.01% | 8,509 |
Institutional holders 489
View all →| Holder | Value | % of shares |
|---|---|---|
| $1.31B | 18.42% | |
| $633.19M | 8.93% | |
| $446.94M | 6.30% | |
| $370.14M | 7.32% | |
| $351.68M | 4.96% | |
| $194.51M | 2.74% | |
| $167.42M | 2.36% | |
| $106.49M | 2.11% | |
| $81.04M | 1.14% | |
| $73.42M | 1.15% |
Activity
Jun 30, 2026View all →
InsidersInstitutions
Who's accumulating and trimming this stock (13F).| Date | Actor | Action | Security | Value | Shares Δ | Position after | Impact |
|---|---|---|---|---|---|---|---|
| Q1 2026 as of | Norges Bank 13F manager | Exit | Common stock | $-66.53M | -2.3M -100.00% | 0 | high |
| Q1 2026 as of | AQR Capital Management, LLC 13F manager | Trim | Common stock | $-24.49M | -944K -65.03% | 507,843 0.21% of shares | medium |
| Q4 2025 as of | Norges Bank 13F manager | Add | Common stock | $16.75M | +578K +33.65% | 2,294,097 0.94% of shares | medium |
| Q1 2026 as of | Millennium Management LLC 13F manager | Add | Common stock | $14.86M | +570K +931.35% | 631,055 0.26% of shares | medium |
| Q4 2025 as of | Bank of America Corp /De 13F manager | Add | Common stock | $10.41M | +359K +44.96% | 1,157,427 0.47% of shares | medium |
| Q2 2026 as of | BlackRock, Inc. 13F manager | Add | Common stock | $9.26M | +448K +2.57% | 17,906,984 7.32% of shares | medium |
| Q2 2026 as of | Mawer Investment Management Ltd. 13F manager | New | Common stock | $7.64M | +370K | 369,557 0.15% of shares | medium |
| Q1 2026 as of | Two Sigma Investments, LP 13F manager | Add | Common stock | $6.84M | +262K +41.10% | 900,177 0.37% of shares | medium |
5%+ ownership events
Schedule 13D / 13G
| Filer | Stance | % of class |
|---|---|---|
| Vanguard Group Inc | Passive13G/A | — |
Securities
via CUSIP / OpenFIGI
| Symbol | Type | CUSIP |
|---|---|---|
| AMTM | — | 023939101 |