Quantumsphere AcquisitionQUMSU
13F holders, Q4 2025 (December 31)9holders −21
1new positions
5sold out
$10.18avg. 13F price*
At the end of Q4 2025, 9 institutions reported holding Quantumsphere Acquisition Co. (QUMSU) in their 13F filings, down 21 from Q3 2025. 1 opened new positions and 5 sold out. The largest holders were Rivernorth Capital Management, LLC ($4.3M), Polar Asset Management Partners Inc. ($4.1M) and Westchester Capital Management, LLC ($1.0M).
- Company
- Quantumsphere Acquisition Co.
- CUSIP
- G7387B122
- Latest filing quarter
- Q2 2026
History
Number of 13F holders
Total Exit/New Position Q3 2025 → Q4 2025
| Institutions | Total Value | |
|---|---|---|
| New Positions | 1 | $5K |
| Exits | 5 | $9.2M |
All 13F filers, Q3 2025 → Q4 2025: 1,563 shares bought and 1,112,534 shares sold, net −1,110,971 shares. Counts holders who added, trimmed, opened or closed a position; split-adjusted.
Ownership 9 holders
| Rivernorth Capital Management, LLC | 0.21% | Reduce -0.1% | 424,512 | $4.3M |
| Polar Asset Management Partners Inc. | 0.10% | No change | 400,000 | $4.1M |
| Westchester Capital Management, LLC | 0.05% | No change | 100,000 | $1.0M |
| GABELLI & Co INVESTMENT ADVISERS, INC. | 0.10% | No change | 67,700 | $689K |
| Gabelli Funds LLC | 0.00% | No change | 57,300 | $583K |
| HRT Financial LP | 0.00% | Add +3.7% | 31,089 | $316K |
| Clear Street Group Inc. | 0.00% | Reduce -93.2% | 14,866 | $151K |
| JPMorgan Chase & Co. | 0.00% | No change | 10,000 | $102K |
| UBS Group AG | 0.00% | New | 459 | $5K |
"% of holder's portfolio" is QUMSU's weight in each manager's 13F, not the share of Quantumsphere Acquisition Co. the manager owns.