Comparable stake leader
Dialectic Technology SPV LLC
SEC ownership of QUANTUM CORP /DE/
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0000709283.
Disclosed value leader
John A. Fichthorn
Comparable rows
6/50
Latest evidence
01 Oct 2026
- Public ticker
- QMCO on Nasdaq
- Parsed ownership sources
-
13D/G, 3/4/5, and 13F
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
Dialectic Technology SPV LLC
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
6 of 50
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
Dialectic Technology SPV LLC
Source: Latest parsed Schedule 13D/G stake
- Latest parsed ownership date
-
01 Oct 2026
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0000709283
- Issuer location
- Centennial, CO
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
3 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of QUANTUM CORP /DE/ (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
Dialectic Technology SPV LLC
Disclosed value leader
John A. Fichthorn
Comparable rows
6/50
Latest evidence
01 Oct 2026
13D/G
3/4/5
13F
Lead comparable stake: 40%
44 rows are not safely comparable across share classes.
13D/G row: Dialectic Technology SPV LLC
Showing 1-8 of 50 holder rows.
Quick read
Dialectic Technology SPV LLC leads the comparable SEC ownership view at 40%.
6 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens Dialectic Technology SPV LLC's linked filing trail.
Comparable ownership
Top 5
Dialectic Technology SPV LLC
40%
Alyeska Investment Group, L.P.
6.7%
Two Seas Capital LP
6.3%
OAKTREE CAPITAL MANAGEMENT LP
5.1%
VANGUARD GROUP INC
5%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| Dialectic Technology SPV LLC |
13D/G
3/4/5
JOHN FICHTHORN · 10%+ Owner
|
40%
Reported 13D/G
· 04 Jun 2026
|
$151,021,051
16,892,735 shares
|
+$64,381,473 | 04 Jun 2026 |
| Alyeska Investment Group, L.P. |
13F
13D/G
Company
|
6.7%
Reported 13D/G
· 30 Jun 2026
|
$29,193,208
2,653,928 shares
|
— | 30 Jun 2026 |
| Two Seas Capital LP |
13F
13D/G
Company
|
6.3%
Reported 13D/G
· 30 Jun 2026
|
$27,373,885
2,488,535 shares
|
— | 30 Jun 2026 |
| OAKTREE CAPITAL MANAGEMENT LP |
13F
13D/G
Company
|
5.1%
Reported 13D/G
· 30 Jun 2026
|
$22,128,458
2,011,678 shares
|
— | 30 Jun 2026 |
| VANGUARD GROUP INC |
13D/G
The Vanguard Group
|
5%
Reported 13D/G
· 31 Dec 2024
|
$2,714,883
242,184 shares
|
$0 | 31 Dec 2024 |
| Blue Torch Capital LP |
13D/G
|
2.3%
Reported 13D/G
· 13 Feb 2025
|
$1,521,903
135,763 shares
|
-$3,029,110 | 13 Feb 2025 |
| John A. Fichthorn |
3/4/5
Director, 10%+ Owner
|
—
mixed-class rows
|
$155,600,676
14,251,427 shares
mixed-class rows
|
— | 01 Oct 2026 |
| BRC Group Holdings, Inc. |
3/4/5
10%+ Owner
|
—
denominator unverified
|
$2,519,591
5,399,896 shares
|
— | 30 Sep 2021 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Net insider flow leans to selling over the last 12 months. Net value: -$84,680.
Buys
$0
Insiders: 0
Sells
$84,680
Insiders: 3
Net
-$84,680
Shares: -8,079
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 8,079
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 1,478 | $0 | $15,856 | -$15,856 |
| 3-6 | 0 | 6,492 | $0 | $68,231 | -$68,231 |
| 6-9 | 0 | 109 | $0 | $593 | -$593 |
| 9-12 | 0 | 0 | $0 | $0 | $0 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-20 of 27 reporting-owner rows connected to QUANTUM CORP /DE/. Open a relationship link for the CIK-to-CIK filing trail.
Rows
27
Largest Forms 3/4/5 holder
John A. Fichthorn
Net 12M change
-$84.68K
Full value: -$84,680 · USD · 12-month changeLatest report
01 Oct 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| John A. Fichthorn | Director, 10%+ Owner | $155,600,676 | Mixed | 01 Oct 2026 | ||
| Dialectic Technology SPV LLC | 10%+ Owner | $66,996,945 | Mixed | 04 Jun 2026 | ||
| BRC Group Holdings, Inc. | 10%+ Owner | $2,519,591 | Mixed | 30 Sep 2021 | ||
| James C. Clancy | Chief Operating Officer | $1,793,000 | Mixed | 01 Oct 2026 | ||
| Hugues Meyrath | President & CEO, Director | $1,245,098 | -$65,498 | -5% | Filing P/S | 01 Oct 2026 |
| James J. Lerner | President & CEO, Director | $1,069,550 | Filing P/S | 21 Apr 2025 | ||
| Kenneth P. Gianella | Chief Financial Officer | $697,583 | Filing P/S | 03 Feb 2025 | ||
| Yue Zhou White | Director | $584,529 | Mixed | 01 Oct 2026 | ||
| Don Jaworksi | Director | $568,425 | Mixed | 01 Oct 2026 | ||
| Hiral A. Patel | Chief Accounting Officer | $550,000 | Mixed | 01 Oct 2026 | ||
| Henk Jan Spanjaard | Chief Revenue Officer | $531,739 | Filing P/S | 16 Jan 2025 | ||
| John R. Tracy | Director | $429,000 | Mixed | 01 Oct 2026 | ||
| J. Michael Dodson | Senior Vice President, CFO | $406,116 | Mixed | 05 Oct 2022 | ||
| Brian E. Cabrera | SVP Chief Admin Ofcr & Secy | $277,267 | Filing P/S | 21 Apr 2025 | ||
| Tony J. Blevins | Director | $275,000 | Mixed | 01 Oct 2026 | ||
| Lewis W. Moorehead | Chief Accounting Officer | $240,940 | Filing P/S | 21 Apr 2025 | ||
| John Hurley | Chief Revenue Officer | $159,353 | Mixed | 05 Sep 2023 | ||
| William Hillis White | Chief Financial Officer | $158,000 | Mixed | 04 Mar 2026 | ||
| Anthony Craythorne | Chief Revenue Officer | $145,065 | -$15,856 | -9.9% | Filing P/S | 01 Oct 2026 |
| Marc E. Rothman | Director | $138,872 | Mixed | 01 Sep 2022 |
Recent insider transactions for QUANTUM CORP /DE/
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Yue Zhou White | QMCO | Common Stock | Award | 29.2% | 12,000 | 53,139 | 01 Oct 2026 | Direct | ||
| Tony J. Blevins | QMCO | Common Stock | Award | 92.3% | 12,000 | 25,000 | 01 Oct 2026 | Direct | ||
| John R. Tracy | QMCO | Common Stock | Award | 44.4% | 12,000 | 39,000 | 01 Oct 2026 | Direct | ||
| John A. Fichthorn | QMCO | Common Stock | Award | 41.5% | 12,000 | 40,896 | 01 Oct 2026 | Direct | ||
| James C. Clancy | QMCO | Common Stock | Award | 1153.8% | 150,000 | 163,000 | 01 Oct 2026 | Direct | ||
| James C. Clancy | QMCO | Employee Stock Option (right to buy) | Award | 400,000 | 400,000 | 01 Oct 2026 | Direct | |||
| Hugues Meyrath | QMCO | Employee Stock Option (right to buy) | Award | 500,000 | 500,000 | 01 Oct 2026 | Direct | |||
| Hiral A. Patel | QMCO | Common Stock | Award | 50,000 | 50,000 | 01 Oct 2026 | Direct | |||
| Don Jaworksi | QMCO | Common Stock | Award | 30.2% | 12,000 | 51,675 | 01 Oct 2026 | Direct | ||
| Anthony Craythorne | QMCO | Employee Stock Option (right to buy) | Award | 200,000 | 200,000 | 01 Oct 2026 | Direct | |||
| Anthony Craythorne | QMCO | Common Stock | Sale | -9.85% | -$15,856 | $10.73 | -1,478 | 13,522 | 03 Aug 2026 | Direct |
| Laura A. Nash | QMCO | Common Stock | Sale | -2.36% | -$2,733 | $10.51 | -260 | 10,770 | 02 Jul 2026 | Direct |
| Hugues Meyrath | QMCO | Common Stock | Sale | -5% | -$65,498 | $10.51 | -6,232 | 118,468 | 02 Jul 2026 | Direct |
| John A. Fichthorn | QMCO | Common Stock | Award | 28% | 3,083,975 | 14,104,620 | 04 Jun 2026 | by Dialectic Technology SPV LLC | ||
| John A. Fichthorn | QMCO | Common Stock | Conversion of derivative security | 11,020,645 | 11,020,645 | 04 Jun 2026 | by Dialectic Technology SPV LLC | |||
| John A. Fichthorn | QMCO | Convertible Notes | Conversion of derivative security | -100% | -57,241,228 | 0 | 04 Jun 2026 | by Dialectic Technology SPV LLC | ||
| Dialectic Technology SPV LLC | QMCO | Common Stock | Award | 28% | 3,083,975 | 14,104,620 | 04 Jun 2026 | Direct | ||
| Dialectic Technology SPV LLC | QMCO | Common Stock | Conversion of derivative security | 11,020,645 | 11,020,645 | 04 Jun 2026 | Direct | |||
| Dialectic Technology SPV LLC | QMCO | Convertible Notes | Conversion of derivative security | 0 | 0 | 04 Jun 2026 | Direct | |||
| John A. Fichthorn | QMCO | Warrant (right to buy) | Other | 105,911 | 105,911 | 01 Jun 2026 | by Dialectic Technology SPV LLC | |||
| Dialectic Technology SPV LLC | QMCO | Warrant (right to buy) | Other | 105,911 | 105,911 | 01 Jun 2026 | Direct | |||
| Laura A. Nash | QMCO | Common Stock | Sale | -0.98% | -$593 | $5.44 | -109 | 11,030 | 02 Apr 2026 | Direct |
| Laura A. Nash | QMCO | Employee Stock Option (right to buy) | Award | 49,500 | 49,500 | 01 Apr 2026 | Direct | |||
| Anthony Craythorne | QMCO | Employee Stock Option (right to buy) | Award | 148,500 | 148,500 | 01 Apr 2026 | Direct | |||
| Hugues Meyrath | QMCO | Employee Stock Option (right to buy) | Award | 850,000 | 850,000 | 01 Apr 2026 | Direct | |||
| William Hillis White | QMCO | Common Stock | Award | 25,000 | 25,000 | 04 Mar 2026 | Direct | |||
| Anthony Craythorne | QMCO | Common Stock | Award | 15,000 | 15,000 | 01 Jan 2026 | Direct | |||
| Hugues Meyrath | QMCO | Common Stock | Award | 100.5% | 62,500 | 124,700 | 01 Jan 2026 | Direct | ||
| Hugues Meyrath | QMCO | Employee Stock Option (right to buy) | Award | 50,000 | 50,000 | 01 Jan 2026 | Direct | |||
| Yue Zhou White | QMCO | Common Stock | Award | 41.2% | 12,000 | 41,139 | 01 Jan 2026 | Direct | ||
| James C. Clancy | QMCO | Common Stock | Award | 1200% | 12,000 | 13,000 | 01 Jan 2026 | Direct | ||
| Tony J. Blevins | QMCO | Common Stock | Award | 1200% | 12,000 | 13,000 | 01 Jan 2026 | Direct | ||
| Don Jaworksi | QMCO | Common Stock | Award | 43.4% | 12,000 | 39,675 | 01 Jan 2026 | Direct | ||
| John A. Fichthorn | QMCO | Common Stock | Award | 78.6% | 12,000 | 27,271 | 01 Jan 2026 | Direct | ||
| John R. Tracy | QMCO | Common Stock | Award | 80% | 12,000 | 27,000 | 01 Jan 2026 | Direct | ||
| John A. Fichthorn | QMCO | Convertible Notes | Other | 0 | 0 | 18 Dec 2025 | by Dialectic Technology SPV LLC | |||
| Dialectic Technology SPV LLC | QMCO | Convertible Notes | Other | 0 | $54,718,114 | 18 Dec 2025 | Direct | |||
| James C. Clancy | QMCO | Common Stock | Award | 1,000 | 1,000 | 01 Nov 2025 | Direct | |||
| Tony J. Blevins | QMCO | Common Stock | Award | 1,000 | 1,000 | 01 Nov 2025 | Direct | |||
| Hugues Meyrath | QMCO | Common Stock | Award | 151.8% | 37,500 | 62,200 | 01 Nov 2025 | Direct | ||
| Hugues Meyrath | QMCO | Employee Stock Option (right to buy) | Award | 50,000 | 50,000 | 01 Nov 2025 | Direct |
* marks a reported price that did not pass the local price check.