QUANTUM CORP (QMCO) Institutional Shareholders
QUANTUM CORP (QMCO) is currently reported in institutional portfolios tracked by InsiderSet based on the latest available SEC Form 13F filings for the quarter ended June 30, 2026. The institutional investors covered on this page collectively reported approximately $158.07M in QMCO holdings during the latest filing period.
Alyeska Investment Group, L.P. is currently the largest disclosed institutional shareholder of QMCO tracked by InsiderSet, reporting ownership valued at approximately $29.19M in its June 30, 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 $66.59M, representing an estimated gain of +128.09% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 85% of the total disclosed QMCO value among the investors covered in this analysis. Major shareholders include Alyeska Investment Group, L.P., Two Seas Capital Lp, Oaktree Capital Management, and several other long-term asset managers with concentrated positions in QUANTUM CORP (QMCO).
This page ranks the largest institutional QMCO 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
59
Total Reported Value
$158.07M
Largest Holder
Alyeska Investment Group, L.P.
Largest Position
$29.19M
Insider Transactions (90d)
0
Latest Filing Quarter
Q2 2026
New Institutional Positions
73
Funds Exiting Positions
0
| Name | Investor/Manager | Portfolio % | Quantity | Reported Balance | Current Estimated Value | Gain/loss Since Filing | Estimated Portfolio Performance |
|---|---|---|---|---|---|---|---|
| Alyeska Investment Group, L.P. | 0.08% | 2,653,928 | $29,193,208 | $66,587,054 | +$37,393,846 | +128.09% | |
| Two Seas Capital Lp | 1.04% | 2,488,535 | $27,373,885 | $62,437,343 | +$35,063,458 | +128.09% | |
| Oaktree Capital Management | Howard Marks | 0.42% | 2,011,678 | $22,128,458 | $50,473,001 | +$28,344,543 | +128.09% |
| Neuberger Berman Group Llc | 0.01% | 1,163,315 | $12,796,465 | $29,187,573 | +$16,391,108 | +128.09% | |
| Portolan Capital Management, Llc | 0.42% | 1,020,120 | $11,221,320 | $25,594,811 | +$14,373,491 | +128.09% | |
| Ashford Capital Management Inc | 1.13% | 1,039,200 | $10,551,200 | $26,073,528 | +$15,522,328 | +147.11% | |
| Marshall Wace, Llp | 0.01% | 713,075 | $7,843,825 | $17,891,052 | +$10,047,227 | +128.09% | |
| Vanguard Capital Management Llc | 0.00% | 605,541 | $6,660,951 | $15,193,024 | +$8,532,073 | +128.09% | |
| Manatuck Hill Partners, Llc | 1.28% | 350,000 | $3,850,000 | $8,781,500 | +$4,931,500 | +128.09% | |
| Blackrock, Inc. | 0.00% | 273,030 | $3,003,330 | $6,850,323 | +$3,846,993 | +128.09% | |
| Cinctive Capital Management Lp | 0.08% | 182,769 | $2,010,459 | $4,585,674 | +$2,575,215 | +128.09% | |
| Bank Of America Corp | 0.00% | 170,130 | $1,871,430 | $4,268,562 | +$2,397,132 | +128.09% | |
| Geode Capital Management, Llc | 0.00% | 164,600 | $1,811,524 | $4,129,814 | +$2,318,290 | +127.97% | |
| Renaissance Technologies LLC | Jim Simons | 0.00% | 154,516 | $1,699,676 | $3,876,806 | +$2,177,130 | +128.09% |
| Sona Asset Management (Us) Llc | 0.06% | 150,000 | $1,650,000 | $3,763,500 | +$2,113,500 | +128.09% | |
| Walleye Capital Llc | 0.01% | 120,044 | $1,320,484 | $3,011,904 | +$1,691,420 | +128.09% | |
| Raymond James Financial Inc | 0.00% | 103,836 | $1,142,196 | $2,605,245 | +$1,463,049 | +128.09% | |
| Centiva Capital, Lp | 0.04% | 100,000 | $1,100,000 | $2,509,000 | +$1,409,000 | +128.09% | |
| Vanguard Fiduciary Trust Co | 0.00% | 89,125 | $980,375 | $2,236,146 | +$1,255,771 | +128.09% | |
| Kkm Financial Llc | 0.13% | 90,274 | $960,515 | $2,264,975 | +$1,304,460 | +135.81% | |
| Qube Research & Technologies Ltd | 0.00% | 80,977 | $890,747 | $2,031,713 | +$1,140,966 | +128.09% | |
| State Street Corp | 0.00% | 75,914 | $835,054 | $1,904,682 | +$1,069,628 | +128.09% | |
| Cygnus Capital Advisors, Llc | 0.56% | 74,323 | $818,000 | $1,864,764 | +$1,046,764 | +127.97% | |
| Susquehanna International Group, Llp | 0.00% | 69,775 | $767,525 | $1,750,655 | +$983,130 | +128.09% | |
| Man Group Plc | 0.00% | 68,593 | $754,523 | $1,720,998 | +$966,475 | +128.09% | |
| Informed Momentum Co Llc | 0.06% | 64,857 | $713,427 | $1,627,262 | +$913,835 | +128.09% | |
| Ubs Group Ag | 0.00% | 46,106 | $507,166 | $1,156,800 | +$649,634 | +128.09% | |
| Sei Investments Co | 0.00% | 38,739 | $426,150 | $971,962 | +$545,812 | +128.08% | |
| Susquehanna Fundamental Investments, Llc | 0.01% | 34,601 | $380,611 | $868,139 | +$487,528 | +128.09% | |
| Squarepoint Ops Llc | 0.00% | 33,817 | $371,987 | $848,469 | +$476,482 | +128.09% | |
| Northern Trust Corp | 0.00% | 33,220 | $365,420 | $833,490 | +$468,070 | +128.09% | |
| Price T Rowe Associates Inc | 0.00% | 25,069 | $276,000 | $628,981 | +$352,981 | +127.89% | |
| Millennium Management Llc | 0.00% | 21,755 | $239,305 | $545,833 | +$306,528 | +128.09% | |
| Goldman Sachs Group Inc | 0.00% | 19,153 | $210,683 | $480,549 | +$269,866 | +128.09% | |
| Bridgeway Capital Management, Llc | 0.00% | 16,240 | $178,640 | $407,462 | +$228,822 | +128.09% | |
| Morgan Stanley | 0.00% | 15,492 | $170,412 | $388,694 | +$218,282 | +128.09% | |
| Citigroup Inc | 0.00% | 14,426 | $158,686 | $361,948 | +$203,262 | +128.09% | |
| Kovack Advisors, Inc. | 0.01% | 13,430 | $146,790 | $336,959 | +$190,169 | +129.55% | |
| Schonfeld Strategic Advisors Llc | 0.00% | 12,055 | $132,605 | $302,460 | +$169,855 | +128.09% | |
| Wells Fargo & Company/Mn | 0.00% | 11,300 | $124,300 | $283,517 | +$159,217 | +128.09% | |
| Flagship Harbor Advisors, Llc | 0.00% | 11,004 | $121,044 | $276,090 | +$155,046 | +128.09% | |
| Invesco Ltd. | 0.00% | 10,839 | $119,229 | $271,951 | +$152,722 | +128.09% | |
| Vanguard Global Advisers, Llc | 0.00% | 6,000 | $66,000 | $150,540 | +$84,540 | +128.09% | |
| Jpmorgan Chase & Co | 0.00% | 3,680 | $43,608 | $92,331 | +$48,723 | +111.73% | |
| Jones Financial Companies Lllp | 0.00% | 1,580 | $18,407 | $39,642 | +$21,235 | +115.36% | |
| Bnp Paribas Financial Markets | 0.00% | 1,187 | $13,057 | $29,782 | +$16,725 | +128.09% | |
| Federated Hermes, Inc. | 0.00% | 1,158 | $12,738 | $29,054 | +$16,316 | +128.09% | |
| Sbi Securities Co., Ltd. | 0.00% | 1,070 | $11,770 | $26,846 | +$15,076 | +128.09% | |
| Royal Bank Of Canada | 0.00% | 765 | $8,000 | $19,194 | +$11,194 | +139.92% | |
| Tower Research Capital Llc (Trc) | 0.00% | 655 | $7,205 | $16,434 | +$9,229 | +128.09% |
Frequently asked questions about QMCO
Who owns the most QMCO stock?
The largest holders of QMCO 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 QUANTUM CORP (QMCO).
Is QMCO widely held by superinvestors?
Many widely followed stocks like QMCO appear across numerous superinvestor portfolios because of liquidity, index inclusion, and fundamentals. The holder count and table above show how broadly QMCO 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.