QUANTUM CORP QMCO
COM · Common Stock · CUSIP 747906600
- SectorTechnology
- IndustryComputer Storage Devices
- HeadquartersCentennial, CO
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once. Holder counts are more reliable. Shares outstanding: 14.6m as of 2026-02-12, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $4.75.
Trends to Q1 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2024 | 26 |
| Q4 2024 | 46 |
| Q1 2025 | 30 |
| Q2 2025 | 36 |
| Q3 2025 | 29 |
| Q4 2025 | 40 |
| Q1 2026 | 37 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q4 2024 | 30 | 12 |
| Q1 2025 | 20 | 26 |
| Q2 2025 | 22 | 15 |
| Q3 2025 | 16 | 14 |
| Q4 2025 | 29 | 14 |
| Q1 2026 | 16 | 22 |
Biggest buyers
| SONA ASSET MANAGEMENT (US) LLC | New | +70.1k |
| Cygnus Capital Advisors, LLC | Added | +54.7k |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC | New | +16.2k |
| MARSHALL WACE, LLP | Added | +15.8k |
| Kovack Advisors, Inc. | New | +12.5k |
| R Squared Ltd | New | +12.2k |
| MORGAN STANLEY | Added | +10.9k |
| LPL Financial LLC | Added | +6.2k |
| PRICE T ROWE ASSOCIATES INC /MD/ | Added | +5.9k |
| GEODE CAPITAL MANAGEMENT, LLC | Added | +2.3k |
Biggest sellers
| Portolan Capital Management, LLC | Sold out | -477.2k |
| UBS Group AG | Reduced | -66.8k |
| AlphaQuest LLC | Sold out | -29.4k |
| STATE STREET CORP | Reduced | -17.9k |
| Engineers Gate Manager LP | Sold out | -16.4k |
| CITIGROUP INC | Sold out | -12.8k |
| MILLENNIUM MANAGEMENT LLC | Sold out | -11.2k |
| FLAGSHIP HARBOR ADVISORS, LLC | Reduced | -9.4k |
| LANARK FINANCIAL, INC. | Sold out | -4.0k |
| BlackRock, Inc. | Reduced | -3.2k |
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
Dialectic Technology SPV LLC
13D · may seek influence
-1.4 pts · filed 2026-06-08
Stated purposeItem 4 of the Amended Statement is hereby amended by adding the following paragraphs to the end of Item 4: Entry into Conversion Agreement On June 4, 2026 (the "Closing"), the Company issued and sold to certain accredited investors in a private placement (the "Private Placement"), an aggregate of 10,615,712 shares of Common Stock. In order to facilitate, among other things, the Private Placement, Dialectic, as the sole beneficial owner of the Convertible Notes issued under the Indenture, agreed to voluntarily convert the Convertible Notes into Common Stock. Pursuant to a Conversion Agreement dated June 1, 2026 (the "Conversion Agreement"), by and among the Company, Dialectic and, solely with respect to Sections 7.1 and 7.3 and Articles III and X thereof, U.S. Bank Trust Company, Nationa… Full filing |
40.0% |
| Alyeska Investment Group, L.P. 13G · institution new · filed 2026-08-14 | 6.7% |
| Two Seas Capital LP 13G · institution new · filed 2026-08-14 | 6.3% |
| OAKTREE CAPITAL MANAGEMENT LP 13G · institution new · filed 2026-08-10 | 5.1% |
Insider purchases and sales in Q1 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q2 2024 | 0 | — | 0 | — | — |
| Q3 2024 | 0 | — | 0 | — | — |
| Q4 2024 | 0 | — | 5 | $35.3k | — |
| Q1 2025 | 0 | — | 4 | $274.8k | — |
| Q2 2025 | 0 | — | 4 | $40.7k | — |
| Q3 2025 | 0 | — | 1 | $2.1k | — |
| Q4 2025 | 0 | — | 2 | $40.1k | — |
| Q1 2026 | 0 | — | 0 | — | — |
None reported in Q1 2026.
Holders, Q1 2026
| Manager | Shares | Change |
|---|---|---|
| VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 539.3k $2.6m | First filing |
| BlackRock, Inc. 0.00% of their portfolio | 217.5k $1.0m | Reduced -3.2k |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 159.2k $756.5k | Added +2.3k |
| Cygnus Capital Advisors, LLC 0.40% of their portfolio | 124.1k $590.0k | Added +54.7k |
| UBS Group AG 0.00% of their portfolio | 99.1k $470.6k | Reduced -66.8k |
| VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio | 80.3k $381.2k | First filing |
| STATE STREET CORP 0.00% of their portfolio | 72.8k $345.9k | Reduced -17.9k |
| SONA ASSET MANAGEMENT (US) LLC 0.01% of their portfolio | 70.1k $332.9k | New |
| MARSHALL WACE, LLP 0.00% of their portfolio | 37.5k $178.3k | Added +15.8k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 28.8k $136.6k | Unchanged |
| LPL Financial LLC 0.00% of their portfolio | 24.6k $116.8k | Added +6.2k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 21.8k $104.0k | Added +5.9k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 20.5k $97.3k | Reduced -50 |
| FLAGSHIP HARBOR ADVISORS, LLC 0.00% of their portfolio | 17.2k $81.6k | Reduced -9.4k |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 16.2k $77.1k | New |
| MORGAN STANLEY 0.00% of their portfolio | 15.2k $72.1k | Added +10.9k |
| Kovack Advisors, Inc. 0.00% of their portfolio | 12.5k $62.8k | New |
| BARCLAYS PLC 0.00% of their portfolio | 12.4k $59.1k | Reduced -1.8k |
| R Squared Ltd 0.03% of their portfolio | 12.2k $58.2k | New |
| XTX Topco Ltd 0.00% of their portfolio | 11.3k $53.8k | Reduced -627 |
| Vanguard Global Advisers, LLC 0.00% of their portfolio | 6.0k $28.5k | First filing |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 4.1k $19.6k | Added +600 |
| SBI Securities Co., Ltd. 0.00% of their portfolio | 2.0k $9.5k | Reduced -421 |
| HOLLENCREST CAPITAL MANAGEMENT 0.00% of their portfolio | 2.0k $9.5k | New |
| JONES FINANCIAL COMPANIES LLLP 0.00% of their portfolio | 1.5k $6.9k | Reduced -374 |
| OSAIC HOLDINGS, INC. 0.00% of their portfolio | 965 $4.6k | Added +217 |
| FEDERATED HERMES, INC. 0.00% of their portfolio | 835 $4.0k | Added +334 |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 261 $1.2k | Reduced -758 |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 128 $1.0k | Reduced -705 |
| NATIONAL BANK OF CANADA /FI/ 0.00% of their portfolio | 100 $475 | Unchanged |
| EFG International AG 0.00% of their portfolio | 100 $477 | Unchanged |
| Rialto Wealth Management, LLC 0.00% of their portfolio | 87 $414 | New |
| Lavaca Capital LLC 0.00% of their portfolio | 39 $185 | New |
| Federation des caisses Desjardins du Quebec 0.00% of their portfolio | 25 $119 | Unchanged |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 8 $34 | Unchanged |
| Farther Finance Advisors, LLC 0.00% of their portfolio | 4 $20 | Unchanged |
| Activest Wealth Management 0.00% of their portfolio | 1 $4 | Unchanged |