Quantumsphere Acquisition Corp
QUMSU- 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; 7 institutions reported holding it in 13F filings for Q2 2026, worth $1.95M in total; no superinvestor holds it.
13F holders, Q4 2025
Institutional positions in Quantumsphere Acquisition Corp as of Dec 31, 2025. Investment managers with $100 million or more in US stocks report their long positions on Form 13F within 45 days after each quarter ends. How 13F works
- Institutional holders
- 9
- −20 vs. Q3 2025
- Shares held
- 1.11M
- −4.39M (−79.9%) vs. Q3 2025
- Total value
- $11.3M
- −$44.4M (−79.8%) vs. Q3 2025
- New holders
- 1
- 1 more added
- Sold out
- 21
- 2 more reduced
1 institution that held it in Q3 2025 haven't filed for Q4 2025 yet. Not filing isn't selling, so they aren't counted as sold out or in the changes above.
Compare with Q3 2025: new holders, sold out and not filed yet
Holders and value by quarter
Institutions reporting QUMSU on Form 13F each quarter since Q1 2021, and the total value they reported. Values are as of each quarter end, so they also move with the share price.
| Quarter | Holders | Value |
|---|---|---|
| Q2 2026 | 7 | $1.95M |
| Q1 2026 | 8 | $2.94M |
| Q4 2025 | 9 | $11.3M |
| Q3 2025 | 30 | $56.7M |
| Q2 2025 | 0 | $0 |
| Q1 2025 | 0 | $0 |
| Q4 2024 | 0 | $0 |
| Q3 2024 | 0 | $0 |
| Q2 2024 | 0 | $0 |
| Q1 2024 | 0 | $0 |
| Q4 2023 | 0 | $0 |
| Q3 2023 | 0 | $0 |
| Q2 2023 | 0 | $0 |
| Q1 2023 | 0 | $0 |
| Q4 2022 | 0 | $0 |
| Q3 2022 | 0 | $0 |
| Q2 2022 | 0 | $0 |
| Q1 2022 | 0 | $0 |
| Q4 2021 | 0 | $0 |
| Q3 2021 | 0 | $0 |
| Q2 2021 | 0 | $0 |
| Q1 2021 | 0 | $0 |
Institutions, Q4 2025
Shares, value and share of portfolio for each institution holding Quantumsphere Acquisition Corp; share changes are against Q3 2025.
| Institution | Shares | Value | % of portfolio | Change in shares | Action |
|---|---|---|---|---|---|
| Rivernorth Capital Management, LLC | 424,512 | $4.32M | 0.20% | −488−0.1% | Reduced |
| Polar Asset Management Partners Inc. | 400,000 | $4.07M | 0.08% | 00.0% | Unchanged |
| Westchester Capital Management, LLC | 100,000 | $1.02M | 0.05% | 00.0% | Unchanged |
| Gabelli & Co Investment Advisers, Inc. | 67,700 | $689.2K | 0.10% | 00.0% | Unchanged |
| Gabelli Funds LLC | 57,300 | $583.3K | 0.00% | 00.0% | Unchanged |
| HRT Financial LP | 31,089 | $316.0K | 0.00% | +1,104+3.7% | Added |
| Clear Street Group Inc. | 14,866 | $151.3K | 0.00% | −203,191−93.2% | Reduced |
| JPMorgan Chase & Co | 10,000 | $101.8K | 0.00% | 00.0% | Unchanged |
| UBS Group AG | 459 | $4.67K | 0.00% | +459 | New |
| Glazer Capital, LLC | 0 | $0 | 0.00% | −420,542−100.0% | Sold out |
| Harraden Circle Investments, LLC | 0 | $0 | 0.00% | −400,707−100.0% | Sold out |
| Linden Advisors LP | 0 | $0 | 0.00% | −400,000−100.0% | Sold out |
| Toronto Dominion Bank | 0 | $0 | 0.00% | −361,000−100.0% | Sold out |
| CNH Partners LLC | 0 | $0 | 0.00% | −322,660−100.0% | Sold out |
| HGC Investment Management Inc. | 0 | $0 | 0.00% | −300,000−100.0% | Sold out |
| Meteora Capital, LLC | 0 | $0 | 0.00% | −229,999−100.0% | Sold out |
| Two Sigma Investments, LP | 0 | $0 | 0.00% | −222,490−100.0% | Sold out |
| Cable Car Capital LLC | 0 | $0 | 0.00% | −174,801−100.0% | Sold out |
| StoneX Group Inc. | 0 | $0 | 0.00% | −168,149−100.0% | Sold out |
| Heights Capital Management, Inc | 0 | $0 | 0.00% | −150,000−100.0% | Sold out |
| Radcliffe Capital Management, L.P. | 0 | $0 | 0.00% | −150,000−100.0% | Sold out |
| Wolverine Asset Management LLC | 0 | $0 | 0.00% | −150,000−100.0% | Sold out |
| Berkley W R Corp | 0 | $0 | 0.00% | −148,770−100.0% | Sold out |
| D. E. Shaw & Co., Inc. | 0 | $0 | 0.00% | −125,000−100.0% | Sold out |
| Periscope Capital Inc. | 0 | $0 | 0.00% | −125,000−100.0% | Sold out |
| BNP Paribas Arbitrage, SA | 0 | $0 | 0.00% | −102,340−100.0% | Sold out |
| Boothbay Fund Management, LLC | 0 | $0 | 0.00% | −100,000−100.0% | Sold out |
| Schonfeld Strategic Advisors LLC | 0 | $0 | 0.00% | −87,486−100.0% | Sold out |
| Warberg Asset Management LLC | 0 | $0 | 0.00% | −41,421−100.0% | Sold out |
| TrueMark Investments, LLC | 0 | $0 | 0.00% | −10,000−100.0% | Sold out |
| Atw Spac Management LLC | – | – | – | – | Not filed |