AMENTUM HOLDINGS INC (AMTM) Institutional Shareholders
AMENTUM HOLDINGS INC (AMTM) is currently reported in institutional portfolios tracked by InsiderSet based on the latest available SEC Form 13F filings for the quarter ended March 31, 2026. The institutional investors covered on this page collectively reported approximately $5.05B in AMTM holdings during the latest filing period.
American Securities Llc is currently the largest disclosed institutional shareholder of AMTM tracked by InsiderSet, reporting ownership valued at approximately $1.17B in its March 31, 2026 SEC Form 13F filing. Based on current market prices and the latest disclosed share count, the position is now estimated to be worth approximately $1.09B, representing an estimated loss of -7.44% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 67% of the total disclosed AMTM value among the investors covered in this analysis. Major shareholders include American Securities Llc, Invesco Ltd., Blackrock, Inc., and several other long-term asset managers with concentrated positions in AMENTUM HOLDINGS INC (AMTM).
This page ranks the largest institutional AMTM shareholders using publicly disclosed SEC Form 13F data, including reported values, estimated current holding values, portfolio allocation percentages, ownership concentration metrics, and historical holding changes across major hedge funds and investment firms.
Institutional Holders
469
Total Reported Value
$5.05B
Largest Holder
American Securities Llc
Largest Position
$1.17B
Insider Transactions (90d)
0
Latest Filing Quarter
Q2 2026
New Institutional Positions
57
Funds Exiting Positions
0
| Name | Investor/Manager | Portfolio % | Quantity | Reported Balance | Current Estimated Value | Gain/loss Since Filing | Estimated Portfolio Performance |
|---|---|---|---|---|---|---|---|
| American Securities Llc | 29.88% | 45,026,743 | $1,174,297,457 | $1,086,945,576 | -$87,351,881 | -7.44% | |
| Invesco Ltd. | 0.09% | 21,473,778 | $560,036,140 | $518,377,001 | -$41,659,139 | -7.44% | |
| Blackrock, Inc. | 0.01% | 17,841,283 | $465,300,661 | $430,688,572 | -$34,612,089 | -7.44% | |
| Primecap Management Co/Ca/ | 0.25% | 12,085,294 | $315,184,494 | $291,738,997 | -$23,445,497 | -7.44% | |
| Vanguard Portfolio Management Llc | 0.01% | 7,852,951 | $204,804,962 | $189,570,237 | -$15,234,725 | -7.44% | |
| Vanguard Capital Management Llc | 0.00% | 6,650,879 | $173,454,924 | $160,552,219 | -$12,902,705 | -7.44% | |
| Fmr Llc | 0.01% | 5,578,386 | $145,484,322 | $134,662,238 | -$10,822,084 | -7.44% | |
| State Street Corp | 0.00% | 5,079,041 | $132,461,389 | $122,608,050 | -$9,853,339 | -7.44% | |
| Frontier Capital Management Co Llc | 1.32% | 4,930,210 | $128,579,888 | $119,015,269 | -$9,564,619 | -7.44% | |
| Dimensional Fund Advisors Lp | 0.02% | 3,787,420 | $98,767,206 | $91,428,319 | -$7,338,887 | -7.43% | |
| Geode Capital Management, Llc | 0.00% | 2,814,415 | $73,424,524 | $67,939,978 | -$5,484,546 | -7.47% | |
| Mirae Asset Global Etfs Holdings Ltd. | 0.10% | 2,785,134 | $72,636,295 | $67,233,135 | -$5,403,160 | -7.44% | |
| Focus Partners Wealth | 0.08% | 2,604,911 | $67,936,092 | $62,882,552 | -$5,053,540 | -7.44% | |
| Bank Of America Corp | 0.00% | 2,405,041 | $62,723,470 | $58,057,690 | -$4,665,780 | -7.44% | |
| Morgan Stanley | 0.00% | 2,234,913 | $58,286,592 | $53,950,800 | -$4,335,792 | -7.44% | |
| Arvin Capital Management Lp | 12.62% | 2,071,200 | $54,016,896 | $49,998,768 | -$4,018,128 | -7.44% | |
| Charles Schwab Investment Management Inc | 0.01% | 2,067,930 | $53,931,614 | $49,919,830 | -$4,011,784 | -7.44% | |
| Ubs Group Ag | 0.01% | 1,710,775 | $44,617,011 | $41,298,109 | -$3,318,903 | -7.44% | |
| Point72 Asset Management, L.P. | 0.07% | 1,630,563 | $42,525,083 | $39,361,791 | -$3,163,292 | -7.44% | |
| Sequoia Fund | Ruane, Cunniff & Goldfarb | 0.70% | 1,622,982 | $42,327,370 | $39,178,785 | -$3,148,585 | -7.44% |
| Segra Capital Management, Llc | 32.74% | 1,612,726 | $42,059,894 | $38,931,206 | -$3,128,688 | -7.44% | |
| Permian Investment Partners, Lp | 4.52% | 1,567,000 | $40,867,360 | $37,827,380 | -$3,039,980 | -7.44% | |
| Toronto Dominion Bank | 0.08% | 1,565,223 | $40,821,003 | $37,784,483 | -$3,036,520 | -7.44% | |
| Brightline Capital Management, Llc | 10.77% | 1,396,000 | $36,407,680 | $33,699,440 | -$2,708,240 | -7.44% | |
| Verition Fund Management Llc | 0.33% | 1,297,946 | $33,850,432 | $31,332,416 | -$2,518,016 | -7.44% | |
| Voya Investment Management Llc | 0.03% | 1,199,491 | $31,282,726 | $28,955,713 | -$2,327,013 | -7.44% | |
| Goldman Sachs Group Inc | 0.00% | 1,131,438 | $29,507,908 | $27,312,913 | -$2,194,995 | -7.44% | |
| Loomis Sayles & Co L P | 0.04% | 1,081,336 | $28,201,231 | $26,103,451 | -$2,097,780 | -7.44% | |
| Troluce Capital Advisors Llc | 2.76% | 1,000,000 | $26,080,000 | $24,140,000 | -$1,940,000 | -7.44% | |
| Northern Trust Corp | 0.00% | 984,105 | $25,665,458 | $23,756,295 | -$1,909,163 | -7.44% | |
| Vanguard Fiduciary Trust Co | 0.01% | 947,460 | $24,709,757 | $22,871,684 | -$1,838,073 | -7.44% | |
| Bank Of New York Mellon Corp | 0.00% | 908,599 | $23,696,270 | $21,933,580 | -$1,762,690 | -7.44% | |
| Two Sigma Investments, Lp | 0.02% | 900,177 | $23,476,616 | $21,730,273 | -$1,746,343 | -7.44% | |
| Moore Capital Management, Lp | 0.83% | 873,610 | $22,783,749 | $21,088,945 | -$1,694,804 | -7.44% | |
| Nuveen, Llc | 0.01% | 871,795 | $22,736,413 | $21,045,131 | -$1,691,282 | -7.44% | |
| Avenir Corp | 2.67% | 841,099 | $21,935,862 | $20,304,130 | -$1,631,732 | -7.44% | |
| 683 Capital Management, Llc | 1.87% | 775,000 | $20,212,000 | $18,708,500 | -$1,503,500 | -7.44% | |
| Russell Investments Group, Ltd. | 0.02% | 713,828 | $18,616,072 | $17,231,808 | -$1,384,264 | -7.44% | |
| Ancora Advisors Llc | 0.39% | 703,119 | $18,337,343 | $16,973,293 | -$1,364,050 | -7.44% | |
| Cacti Asset Management Llc | 0.91% | 881,692 | $18,224,574 | $21,284,045 | +$3,059,471 | +16.79% | |
| Fil Ltd | 0.01% | 652,159 | $17,008,307 | $15,743,118 | -$1,265,189 | -7.44% | |
| Wells Fargo & Company/Mn | 0.00% | 636,674 | $16,604,444 | $15,369,310 | -$1,235,134 | -7.44% | |
| Millennium Management Llc | 0.01% | 631,055 | $16,457,914 | $15,233,668 | -$1,224,246 | -7.44% | |
| Principal Financial Group Inc | 0.01% | 742,381 | $15,345,015 | $17,921,077 | +$2,576,062 | +16.79% | |
| Public Sector Pension Investment Board | 0.04% | 549,797 | $14,338,706 | $13,272,100 | -$1,066,606 | -7.44% | |
| Royce & Associates Lp | 0.14% | 549,778 | $14,338,210 | $13,271,641 | -$1,066,569 | -7.44% | |
| Gotham Asset Management, Llc | 0.04% | 521,041 | $13,588,749 | $12,577,930 | -$1,010,819 | -7.44% | |
| Aqr Capital Management Llc | 0.01% | 507,843 | $13,173,450 | $12,259,330 | -$914,120 | -6.94% | |
| Ci Investments Inc. | 0.05% | 420,068 | $10,955,373 | $10,140,442 | -$814,931 | -7.44% | |
| Vident Advisory, Llc | 0.09% | 388,862 | $10,141,519 | $9,387,129 | -$754,390 | -7.44% |
Frequently asked questions about AMTM
Who owns the most AMTM stock?
The largest holders of AMTM are typically major institutional investors such as asset managers and hedge funds reporting on Form 13F. The table above ranks tracked superinvestors by reported position size using the latest available filings for AMENTUM HOLDINGS INC (AMTM).
Is AMTM widely held by superinvestors?
Many widely followed stocks like AMTM appear across numerous superinvestor portfolios because of liquidity, index inclusion, and fundamentals. The holder count and table above show how broadly AMTM is represented among the institutional managers we track.
What do “Current Estimated Value”, “Gain/loss Since Filing”, and “Estimated Portfolio Performance” mean?
Current Estimated Value is reported share quantity from the latest 13F times our most recent split-adjusted U.S. session close. Gain/loss Since Filing is that estimate minus the reported 13F dollar value; Estimated Portfolio Performance is that difference as a percent of the reported value. Green means the estimate is above the filing value; red means below (not purchase cost). If many filers share the same implied filing price per share, the performance % may match across rows. These are not official fund marks or live quotes.