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Livermore
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Quantum Corp

QMCO
Exchange
Nasdaq
Industry
Computer Storage Devices
SEC CIK
0000709283

In the last 90 days, Quantum Corp insiders filed 0 open-market purchases and 3 sales; 60 institutions reported holding it in 13F filings for Q2 2026, worth $158.1M in total; Oaktree Capital is the only superinvestor holding it.

Holders of 5% or more of QMCO

Holders whose latest Schedule 13D or 13G filing reports 5% or more of Quantum Corp, largest stake first. The change is against the holder's previous filing.

Holders of 5% or more of QMCO
HolderLatest formStakeChangeFirst filedLatest filingFiling
Dialectic Technology SPV LLC13D/A40.00%16.9M shares−1.40 ppfrom 41.40%Oct 10, 20254 filingsJun 8, 2026SEC
Alyeska Investment Group, L.P.13G6.74%2.65M sharesNewAug 14, 20261 filingAug 14, 2026SEC
Two Seas Capital LP13G6.30%2.49M sharesNewAug 14, 20261 filingAug 14, 2026SEC
Oaktree Capital Management LPSuperinvestorOaktree Capital13G5.11%2.01M sharesNewAug 10, 20261 filingAug 10, 2026SEC

Stakes are as of each holder's latest filing. Holders whose last filing was in the old format (before December 18, 2024) have no stake on record and are not listed, and after an acquisition or delisting holders usually stop filing.

13D and 13G filings

49 Schedule 13D and 13G filings on Quantum Corp, newest first, including old-format filings without a stake.

Schedule 13D and 13G filings on QMCO
Filed (ET)FilerFormStakeChangeEvent dateFiling
Aug 14, 20264:50 PM ETTwo Seas Capital LPand 2 others13G6.30%2.49M sharesNewJun 30, 2026SEC
Aug 14, 20264:28 PM ETAlyeska Investment Group, L.P.and 2 others13G6.74%2.65M sharesNewJun 30, 2026SEC
Aug 10, 20264:15 PM ETOaktree Capital Management LPSuperinvestorOaktree Capital13G5.11%2.01M sharesNewJun 30, 2026SEC
Jun 8, 20269:14 PM ETDialectic Technology SPV LLCand 2 others13D/A40.00%16.9M shares−1.40 ppfrom 41.40%Jun 4, 2026SEC
Jan 12, 20266:58 PM ETDialectic Technology SPV LLCand 2 others13D/A41.40%9.69M shares+4.10 ppfrom 37.30%Jan 8, 2026SEC
Dec 22, 20258:32 PM ETDialectic Technology SPV LLCand 2 others13D/A37.30%8.14M shares+20.60 ppfrom 16.70%Dec 18, 2025SEC
Oct 10, 20254:20 PM ETDialectic Technology SPV LLCand 2 others13D16.70%2.67M sharesNewSep 23, 2025SEC
May 15, 202512:18 PM ETLong Focus Capital Management, LLCand 1 other13G/A0.00%0 shares–Below 5%Mar 31, 2025SEC
May 8, 202510:53 AM ETADK Soho Fund LPand 2 others13G/A0.00%0 shares–Below 5%Feb 7, 2025SEC
Apr 17, 20254:05 PM ETPacific Investment Management Co LLC13D/A0.00%0 shares−14.70 ppfrom 14.70%Below 5%Apr 15, 2025SEC
Mar 31, 20256:45 PM ETPacific Investment Management Co LLC13D/A14.70%962.1K shares−1.80 ppfrom 16.50%Mar 27, 2025SEC
Mar 21, 20258:11 PM ETPacific Investment Management Co LLC13D/A16.50%962.1K shares−0.20 ppfrom 16.70%Mar 19, 2025SEC
Feb 21, 20257:53 PM ETBlue Torch Capital LPand 1 other13D/A2.30%135.8K shares−5.40 ppfrom 7.70%Below 5%Feb 13, 2025SEC
Jan 31, 20259:56 AM ETVanguard Group Inc13G/A4.99%242.2K shares–Below 5%Dec 31, 2024SEC
Jan 7, 20256:12 PM ETPacific Investment Management Co LLC13D/A16.70%962.1K shares–Jan 3, 2025SEC
Jan 6, 20253:55 PM ETBlue Torch Capital LPand 1 other13D7.70%406.0K sharesNewDec 27, 2024SEC
Feb 14, 2024Long Focus Capital Management, LLC13G/AOld format–––SEC
Feb 13, 2024Vanguard Group Inc13GOld format–New–SEC
Feb 12, 2024Neuberger Berman Group LLC13G/AOld format–––SEC
Jan 17, 2024ADK Soho Fund LP13G/AOld format–––SEC
Dec 4, 2023ADK Soho Fund LP13GOld format–New–SEC
Jul 14, 2023Pacific Investment Management Co LLC13D/AOld format–––SEC
Jun 14, 2023Pacific Investment Management Co LLC13D/AOld format–––SEC
May 11, 2023Long Focus Capital Management, LLC13GOld format–New–SEC
Feb 10, 2023Neuberger Berman Group LLC13G/AOld format–––SEC
Feb 10, 2023Senvest Management, LLC13G/AOld format–––SEC
Aug 24, 2022Pacific Investment Management Co LLC13D/AOld format–––SEC
Aug 12, 2022Pacific Investment Management Co LLC13D/AOld format–––SEC
Aug 8, 2022B. Riley Financial, Inc.13D/AOld format–––SEC
Jul 8, 20224:56 PM ETBlackRock Inc.13G/AOld format–––SEC
Jun 10, 2022B. Riley Financial, Inc.13D/AOld format–––SEC
May 20, 2022Neuberger Berman Group LLC13G/AOld format–––SEC
Apr 28, 2022B. Riley Financial, Inc.13D/AOld format–––SEC
Apr 26, 2022Pacific Investment Management Co LLC13D/AOld format–––SEC
Mar 28, 2022Pacific Investment Management Co LLC13DOld format–––SEC
Mar 11, 20222:13 PM ETBlackRock Inc.13GOld format–––SEC
Feb 14, 2022Neuberger Berman Group LLC13G/AOld format–––SEC
Feb 14, 2022180 Degree Capital Corp.13G/AOld format–––SEC
Feb 9, 2022TCW Group Inc13G/AOld format–––SEC
Feb 9, 2022Senvest Management, LLC13G/AOld format–––SEC
Feb 8, 20225:05 PM ETBlackRock Inc.13GOld format–New–SEC
Nov 18, 2021Senvest Management, LLC13GOld format–New–SEC
Nov 1, 2021B. Riley Financial, Inc.13D/AOld format–––SEC
Apr 28, 2021B. Riley Financial, Inc.13D/AOld format–––SEC
Apr 8, 2021Neuberger Berman Group LLC13GOld format–New–SEC
Feb 16, 2021Pacific Investment Management Co LLC13G/AOld format–––SEC
Feb 8, 2021B. Riley Financial, Inc.13D/AOld format–––SEC
Feb 8, 2021TCW Group Inc13G/AOld format–––SEC
Jan 29, 2021180 Degree Capital Corp.13GOld format–New–SEC

Form 144: proposed insider sales

Notices from officers, directors and other affiliates planning to sell Quantum Corp shares.

No Form 144 notices for Quantum Corp are on file.