Quantumsphere AcquisitionQUMSRPreferred / convertible

13F holders, Q4 2025 (December 31)

23holders +18

19new positions

1sold out

1famous investor

$0.21avg. 13F price*

At the end of Q4 2025, 23 institutions reported holding Quantumsphere Acquisition Co. (QUMSR) in their 13F filings, up 18 from Q3 2025. 19 opened new positions and 1 sold out. The largest holders were Harraden Circle Investments, LLC ($209K), Toronto Dominion Bank ($146K) and Highbridge Capital Management LLC ($144K). One famous investor held it David E. Shaw ( of D. E. Shaw & Co.'s portfolio).

Company: Quantumsphere Acquisition Co.
CUSIP: G7387B114
Latest filing quarter: Q2 2026

History

Number of 13F holders

Total Exit/New Position Q3 2025 → Q4 2025

	Institutions	Total Value
New Positions	19	$706K
Exits	1	$6K

All 13F filers, Q3 2025 → Q4 2025: 4,823,086 shares bought and 458,764 shares sold, net +4,364,322 shares. Counts holders who added, trimmed, opened or closed a position; split-adjusted.

Ownership 23 holders


Harraden Circle Investments, LLC	—	Add +493.4%	993,926	$209K
Toronto Dominion Bank	—	Add +1290.3%	695,137	$146K
Highbridge Capital Management LLC	—	Reduce -2.3%	684,037	$144K
Shaolin Capital Management LLC	—	New	460,000	$97K
Glazer Capital, LLC	—	New	420,536	$88K
Linden Advisors LP	—	New	400,000	$88K
AQR Arbitrage LLC	—	New	322,660	$65K
HGC Investment Management Inc.	—	New	300,000	$63K
Clear Street Group Inc.	—	New	229,252	$48K
Cable Car Capital, LP	—	New	174,801	$37K
Radcliffe Capital Management, L.P.	—	New	150,000	$33K
Wolverine Asset Management LLC	—	New	150,000	$32K
Hudson Bay Capital Management LP	—	Reduce -36.2%	150,000	$32K
Heights Capital Management, Inc.	—	New	149,900	$31K
D. E. Shaw & Co.	—	New	125,000	$26K
Periscope Capital Inc.	—	New	125,000	$26K
BNP Paribas Financial Markets	—	New	102,340	$21K
Boothbay Fund Management, LLC	—	New	100,000	$21K
Schonfeld Strategic Advisors LLC	—	New	54,599	$11K
Meteora Capital, LLC	—	New	36,121	$8K
Berkley W R Corp.	—	New	35,110	$7K
UBS Group AG	—	New	16,104	$3K
Bank of America Corp.	—	New	100	$21

"% of holder's portfolio" is QUMSR's weight in each manager's 13F, not the share of Quantumsphere Acquisition Co. the manager owns.