As of November 10, 2026, 5 holders' latest Schedule 13D or 13G filings report owning 5% or more of Quantum Corp. The largest reported stake is Dialectic Technology SPV LLC's, at 40%. 8 filings are on record since October 10, 2025 (Schedule 13D/A, June 8, 2026).
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Key facts
- · Reporting person: Barclays PLC · Sole voting: 2,139,866 · Shared voting: 69,791 · Sole dispositive: 2,139,866 · Shared dispositive: 69,791 · SCHEDULE 13G, 2026-11-06
- · Reporting person: Alyeska Investment Group, L.P. · Sole voting: 0 · Shared voting: 2,653,928 · Sole dispositive: 0 · Shared dispositive: 2,653,928 · SCHEDULE 13G, 2026-08-14
- · Reporting person: Two Seas Capital LP · Sole voting: 2,488,535 · Shared voting: 0 · Sole dispositive: 2,488,535 · Shared dispositive: 0 · SCHEDULE 13G, 2026-08-14
- · Reporting person: Oaktree Capital Management LP · Sole voting: 2,011,678 · Shared voting: 0 · Sole dispositive: 2,011,678 · Shared dispositive: 0 · SCHEDULE 13G, 2026-08-10
- · Reporting person: Dialectic Technology SPV LLC · Sole voting: 0 · Shared voting: 16,863,839 · Sole dispositive: 0 · Shared dispositive: 16,863,839 · SCHEDULE 13D/A, 2026-06-08
Quantum Corp has 8 Schedule 13D or 13G filings on record since 2025-10-10. 5 holders' latest filing reports 5% or more of common-stock. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Dialectic Technology SPV LLC | 40% | 16,863,839 | SCHEDULE 13D/A, 2026-06-08 | 2026-06-04 |
| Alyeska Investment Group, L.P. | 6.74% | 2,653,928 | SCHEDULE 13G, 2026-08-14 | 2026-06-30 |
| Two Seas Capital LP | 6.3% | 2,488,535 | SCHEDULE 13G, 2026-08-14 | 2026-06-30 |
| Barclays PLC | 5.6% | 2,209,657 | SCHEDULE 13G, 2026-11-06 | 2026-09-30 |
| Oaktree Capital Management LP | 5.11% | 2,011,678 | SCHEDULE 13G, 2026-08-10 | 2026-06-30 |
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More on Quantum Corp and the records around it.
Quantum Corp elsewhere on the record
- Leadership changes Sep 2026
- Who owns it
Companies that share a holder
- Oaktree Capital Management LP also filed stake reports on 3 other companies: MATTHEWS INTERNATIONAL CORPORATION (Oct 2026), SharonAI Holdings Inc. (Aug 2026), Rice Acquisition Corp 3 (Feb 2026)
- Two Seas Capital LP also filed stake reports on 14 other companies: NEKTAR THERAPEUTICS (Sep 2026), Calumet, Inc. (Aug 2026), Sable Offshore Corp. (Aug 2026)
- Alyeska Investment Group, L.P. also filed stake reports on 81 other companies: ABUNDIA GLOBAL IMPACT GROUP, INC. (Aug 2026), Bakkt, Inc. (Aug 2026), BATTALION OIL CORP (Aug 2026)
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Dialectic Technology SPV LLC | 0 | 16,863,839 | 0 | 16,863,839 | SCHEDULE 13D/A, 2026-06-08 |
| Dialectic Technology Manager LLC | 0 | 16,863,839 | 0 | 16,863,839 | SCHEDULE 13D/A, 2026-06-08 |
| John Fichthorn | 28,896 | 16,863,839 | 28,896 | 16,863,839 | SCHEDULE 13D/A, 2026-06-08 |
| Alyeska Investment Group, L.P. | 0 | 2,653,928 | 0 | 2,653,928 | SCHEDULE 13G, 2026-08-14 |
| Alyeska Fund GP, LLC | 0 | 2,653,928 | 0 | 2,653,928 | SCHEDULE 13G, 2026-08-14 |
| Anand Parekh | 0 | 2,653,928 | 0 | 2,653,928 | SCHEDULE 13G, 2026-08-14 |
| Two Seas Capital LP | 2,488,535 | 0 | 2,488,535 | 0 | SCHEDULE 13G, 2026-08-14 |
| Two Seas Capital GP LLC | 2,488,535 | 0 | 2,488,535 | 0 | SCHEDULE 13G, 2026-08-14 |
| Sina Toussi | 2,488,535 | 0 | 2,488,535 | 0 | SCHEDULE 13G, 2026-08-14 |
| Barclays PLC | 2,139,866 | 69,791 | 2,139,866 | 69,791 | SCHEDULE 13G, 2026-11-06 |
| Oaktree Capital Management LP | 2,011,678 | 0 | 2,011,678 | 0 | SCHEDULE 13G, 2026-08-10 |
The latest filing identifies Quantum Corp by CUSIP 747906600 and gives its principal executive office as 10770 E. Briarwood Avenue, Centennial, CO 80112 (SCHEDULE 13G, 2026-11-06).
What the percentages are based on
Percent of class as of June 30, 2026: TSC - 6.3% TSC GP - 6.3% Sina Toussi - 6.3% The shares of Common Stock reported for Item 4 total 2,488,535 shares of Common Stock held by the Global Fund. TSC may be deemed to have sole power to vote and sole power to dispose of the Common Stock held by the Global Fund, through its capacity as investment adviser of the Global Fund.Two Seas Capital LP, SCHEDULE 13G, 2026-08-14
Source of funds (Item 3)
Item 3 of the Amended Statement is hereby amended by adding the following to the end thereof: The information set forth in Item 4 of Amendment No. 3 is incorporated herein by reference.Dialectic Technology SPV LLC, SCHEDULE 13D/A, 2026-06-08
Purpose of Transaction (Item 4)
Dialectic Technology SPV LLC
Item 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, National Association, as the trustee and Notes Collateral Agent under the Indenture, Dialectic converted the entire principal amount of the Convertible Notes, together with all accrued and unpaid interest thereon at the Closing, subject to certain conditions set forth in the Conversion Agreement (the "Conversion"). At the Closing, the Convertible Notes were canceled in accordance with the Indenture, and the Indenture was satisfied and discharged. In connection with the Conversion, at the Closing, the Company issued to Dialectic 11,020,645 shares of Common Stock. At the Closing, as consideration for Dialectic's agreement to voluntarily convert the Convertible Notes, the Company issued to …The first part of Item 4 of the SCHEDULE 13D/A filed 2026-06-08; the filing has the rest
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-10-10 | Dialectic Technology SPV LLC | 16.7% | SCHEDULE 13D |
| 2025-12-22 | Dialectic Technology SPV LLC | 37.3% | SCHEDULE 13D/A |
| 2026-01-12 | Dialectic Technology SPV LLC | 41.4% | SCHEDULE 13D/A |
| 2026-06-08 | Dialectic Technology SPV LLC | 40% | SCHEDULE 13D/A |
| 2026-08-10 | Oaktree Capital Management LP | 5.11% | SCHEDULE 13G |
| 2026-08-14 | Two Seas Capital LP | 6.3% | SCHEDULE 13G |
| 2026-08-14 | Alyeska Investment Group, L.P. | 6.74% | SCHEDULE 13G |
| 2026-11-06 | Barclays PLC | 5.6% | SCHEDULE 13G |
Questions about who owns Quantum Corp
Who owns Quantum Corp?
On this page, 5 holders' latest ownership filings report 5% or more of Quantum Corp: Dialectic Technology SPV LLC (40%, Schedule 13D/A, filed 2026-06-08), Alyeska Investment Group, L.P. (6.74%, Schedule 13G, filed 2026-08-14), Two Seas Capital LP (6.3%, Schedule 13G, filed 2026-08-14), Barclays PLC (5.6%, Schedule 13G, filed 2026-11-06) and Oaktree Capital Management LP (5.11%, Schedule 13G, filed 2026-08-10).
Who are the largest shareholders of Quantum Corp?
By the share each holder's latest filing reports, the largest holders of Quantum Corp on this page are Dialectic Technology SPV LLC (40%), Alyeska Investment Group, L.P. (6.74%) and Two Seas Capital LP (6.3%).
When did Dialectic Technology SPV LLC buy into Quantum Corp?
The filings give report dates, not purchase dates. The earliest filing from Dialectic Technology SPV LLC on this page is the Schedule 13D, filed 2025-10-10, reporting 16.7%; its latest, Schedule 13D/A filed 2026-06-08, reports 40%.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 8 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
Also on the record for Quantum Corp
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| October 9, 2026 | Leadership change: William H. White departs, Chief Financial Officer and Principal Financial Officer, and 1 more | — | Leadership changes | Source |
| September 28, 2026 | Leadership change filing (Form 8-K, Item 5.02) | — | Leadership changes | Source |
| September 1, 2026 | Leadership change filing (Form 8-K, Item 5.02) | — | Leadership changes | Source |
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.