Quantumsphere Acquisition Corp
QUMS- Exchange
- Nasdaq
- Industry
- Blank Checks
- SEC CIK
- 0002070900
No open-market purchases or sales by Quantumsphere Acquisition Corp insiders were filed in the last 90 days; 27 institutions reported holding it in 13F filings for Q2 2026, worth $80.3M in total; no superinvestor holds it.
Holders of 5% or more of QUMS
Holders whose latest Schedule 13D or 13G filing reports 5% or more of Quantumsphere Acquisition Corp, largest stake first. The change is against the holder's previous filing.
| Holder | Latest form | Stake | Change | First filed | Latest filing | Filing |
|---|---|---|---|---|---|---|
| Whiteowl Holdings LLC | 13D | 27.41%3.13M shares | New | Sep 15, 20251 filing | Sep 15, 2025 | SEC |
| Berkley W R Corp | 13G | 7.70%881.4K shares | New | Aug 6, 20261 filing | Aug 6, 2026 | SEC |
| Mizuho Financial Group Inc | 13G | 6.30%718.1K shares | New | Feb 12, 20261 filing | Feb 12, 2026 | SEC |
| Wolverine Asset Management LLC | 13G | 5.03%574.2K shares | New | Nov 7, 20251 filing | Nov 7, 2025 | SEC |
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
6 Schedule 13D and 13G filings on Quantumsphere Acquisition Corp, newest first, including old-format filings without a stake.
| Filed (ET) | Filer | Form | Stake | Change | Event date | Filing |
|---|---|---|---|---|---|---|
| Aug 6, 20264:59 PM ET | Berkley W R Corpand 1 other | 13G | 7.70%881.4K shares | New | Jun 30, 2026 | SEC |
| Feb 17, 20264:15 PM ET | Highbridge Capital Management LLC | 13G/A | 0.00%0 shares | −5.30 ppfrom 5.30%Below 5% | Dec 31, 2025 | SEC |
| Feb 12, 20266:54 AM ET | Mizuho Financial Group Inc | 13G | 6.30%718.1K shares | New | Dec 31, 2025 | SEC |
| Nov 14, 202511:01 AM ET | Highbridge Capital Management LLC | 13G | 5.30%600.0K shares | New | Sep 30, 2025 | SEC |
| Nov 7, 20253:35 PM ET | Wolverine Asset Management LLCand 4 others | 13G | 5.03%574.2K shares | New | Oct 31, 2025 | SEC |
| Sep 15, 20255:00 PM ET | Whiteowl Holdings LLC | 13D | 27.41%3.13M shares | New | Aug 5, 2025 | SEC |
Form 144: proposed insider sales
Notices from officers, directors and other affiliates planning to sell Quantumsphere Acquisition Corp shares.
No Form 144 notices for Quantumsphere Acquisition Corp are on file.