QUANTUMSPHERE ACQUISITION CO QUMS
ORD SHS · Common Stock · CUSIP G7387B106
- SectorBlank check (SPAC)
- IndustryBlank Checks
- HeadquartersNew York, NY
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once. Holder counts are more reliable. Shares outstanding: 10.9m as of 2026-06-29, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $10.20.
Trends to Q2 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2025 | 4 |
| Q4 2025 | 25 |
| Q1 2026 | 29 |
| Q2 2026 | 27 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q4 2025 | 24 | 1 |
| Q1 2026 | 10 | 8 |
| Q2 2026 | 7 | 13 |
Biggest buyers
| MIZUHO SECURITIES USA LLC | Added | +757.0k |
| BERKLEY W R CORP | Added | +372.9k |
| HIGHBRIDGE CAPITAL MANAGEMENT LLC | Added | +256.5k |
| RLH Capital LLC | Added | +150.0k |
| Westchester Capital Management, LLC | Added | +100.0k |
| Quarry LP | New | +75.0k |
| AQR Arbitrage LLC | Added | +4.2k |
Biggest sellers
| HGC Investment Management Inc. | Sold out | -300.0k |
| TORONTO DOMINION BANK | Reduced | -165.6k |
| Shaolin Capital Management LLC | Reduced | -74.2k |
| TWO SIGMA INVESTMENTS, LP | Sold out | -35.3k |
| Periscope Capital Inc. | Reduced | -25.0k |
| Karpus Management, Inc. | Reduced | -24.0k |
| GLAZER CAPITAL, LLC | Reduced | -22.9k |
| Virtu Financial LLC | Sold out | -22.3k |
| Clear Street Group Inc. | Reduced | -10.2k |
| WOLVERINE ASSET MANAGEMENT LLC | Reduced | -1.0k |
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
Whiteowl Holdings LLC
13D · may seek influence
new · filed 2025-09-15
Stated purposeIn connection with the organization of the Issuer, on August 29, 2024, pursuant to a Subscription Agreement, the Issuer issued an aggregate of 2,875,000 ordinary shares as Founder Shares, to the Sponsor for an aggregate purchase price of $25,000. On May 6, 2025, our Sponsor surrendered 460,000 founder shares for no consideration to us for cancellation and as a result, our Sponsor held 2,415,000 founder shares as of May 6, 2025. On August 5, 2025, the Issuer and the Sponsor entered into the First Amendment to the Subscription Agreement, pursuant to which the purchased amount of shares was adjusted to 2,898,000 ordinary shares, of which 378,000 are subject to forfeiture if the underwriters' over-allotment option is not exercised in full. Simultaneously with the consummation of the Issuer's … Full filing |
27.4% |
| BERKLEY W R CORP 13G · institution new · filed 2026-08-06 | 7.7% |
| MIZUHO FINANCIAL GROUP INC 13G · institution new · filed 2026-02-12 | 6.3% |
Fell to 5% or below in the last year: WOLVERINE ASSET MANAGEMENT LLC (3.0%, 2026-10-06), HIGHBRIDGE CAPITAL MANAGEMENT LLC (0.0%, 2026-02-17)
Insider purchases and sales since 1 Apr 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
None reported since 1 Apr 2026.
Holders, Q2 2026
| Manager | Shares | Change |
|---|---|---|
| MIZUHO SECURITIES USA LLC 0.14% of their portfolio | 1.5m $15.0m | Added +757.0k |
| BERKLEY W R CORP 0.44% of their portfolio | 881.4k $9.0m | Added +372.9k |
| WOLVERINE ASSET MANAGEMENT LLC 0.08% of their portfolio | 603.0k $6.2m | Reduced -1.0k |
| Karpus Management, Inc. 0.14% of their portfolio | 469.9k $4.8m | Reduced -24.0k |
| RIVERNORTH CAPITAL MANAGEMENT, LLC 0.21% of their portfolio | 424.1k $4.4m | Reduced -388 |
| D. E. Shaw & Co., Inc. 0.00% of their portfolio | 409.9k $4.2m | Unchanged |
| Shaolin Capital Management LLC 0.24% of their portfolio | 405.8k $4.1m | Reduced -74.2k |
| GLAZER CAPITAL, LLC 0.10% of their portfolio | 400.1k $4.1m | Reduced -22.9k |
| Linden Advisors LP 0.02% of their portfolio | 400.0k $4.1m | Unchanged |
| Polar Asset Management Partners Inc. 0.07% of their portfolio | 400.0k $4.1m | Unchanged |
| HIGHBRIDGE CAPITAL MANAGEMENT LLC 0.13% of their portfolio | 377.6k $3.9m | Added +256.5k |
| Westchester Capital Management, LLC 0.18% of their portfolio | 350.0k $3.6m | Added +100.0k |
| AQR Arbitrage LLC 0.05% of their portfolio | 312.5k $3.2m | Added +4.2k |
| RLH Capital LLC 1.22% of their portfolio | 250.0k $2.6m | Added +150.0k |
| Hudson Bay Capital Management LP 0.01% of their portfolio | 235.0k $2.4m | Unchanged |
| Cable Car Capital, LP 0.08% of their portfolio | 174.8k $1.8m | Unchanged |
| Clear Street Group Inc. 0.01% of their portfolio | 164.8k $1.7m | Reduced -10.2k |
| HEIGHTS CAPITAL MANAGEMENT, INC 0.35% of their portfolio | 150.0k $1.5m | Unchanged |
| Radcliffe Capital Management, L.P. 0.12% of their portfolio | 150.0k $1.5m | Unchanged |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 115.0k $1.2m | Unchanged |
| Crossingbridge Advisors, LLC 0.19% of their portfolio | 107.8k $1.1m | Unchanged |
| TORONTO DOMINION BANK 0.00% of their portfolio | 100.0k $1.0m | Reduced -165.6k |
| Periscope Capital Inc. 0.12% of their portfolio | 75.0k $766.5k | Reduced -25.0k |
| Quarry LP 0.12% of their portfolio | 75.0k $766.5k | New |
| Schonfeld Strategic Advisors LLC 0.00% of their portfolio | 55.0k $562.1k | Unchanged |
| Logan Stone Capital, LLC 0.03% of their portfolio | 14.5k $148.1k | Reduced -5 |
| MORGAN STANLEY 0.00% of their portfolio | 53 $542 | Reduced -10 |