QUMSR · Quantumsphere Acquisition Corp · Holdings

$0.13 At close · Oct 27

Market Cap

$118.63M

11.41M

Volume · Oct 21 4618 Avg daily vol (3M) 31.47K

Institutional ownership from SEC Form 13F filings. Investment managers with more than $100 million in U.S. equities must disclose their positions every quarter, within 45 days of quarter-end, so the holdings shown can lag the market by up to a quarter.

Use institutional holdings through the 13F API or MCP → See every holder of QUMSR: 13F, 13D and 13G, insiders and funds →

Recent SEC filings are still being reconciled. Holder totals and changes may be incomplete until processing catches up.

Quarter:

Holders: 25

Total Value: $1,113,581

Total Shares: 6,536,098

Institutional Ownership Trend

4 quarters

Holder Concentration

Across 25 13F filers · Δ vs Mar 31, 2026

Top Holder

17.8%

+1.9 pts

Top 5

50.9%

−0.9 pts

Top 10

76.4%

−1.1 pts

HHI

804

Broadly held+31

Who Holds QUMSR

Last 4 quarters through Jun 30, 2026

Each kind of 13F filer's share of the common shares 13F filers report. Holder type comes from regulatory records, never the filer's name; style, turnover and horizon are measured from each filer's own 13F book. The quarter selector does not change this card.

Jun 30, 2026: 25 filers, like-for-like change -3.8%; actively managed books -3.8%.

Holder type	Share	Filers	Change	New
Registered adviser	70.6%	15	-5.4%	1
Exempt adviser	1.9%	1	0.0%	0
Bank	11.2%	2	+6.9%	0
Insurer	0.4%	1	-31.3%	0
Non-US	6.2%	2	0.0%	0
Adviser	0.0%	0	—	0
Unknown	9.8%	4	-4.9%	0

Style	Share	Filers	Change	New
Systematic-like	9.6%	3	0.0%	0
Concentrated	6.1%	2	-0.5%	0
Diversified active	84.4%	20	-4.5%	1
Index-like	0.0%	0	—	0

Turnover	Share	Filers	Change	New
Medium turnover	39.1%	11	+5.8%	1
High turnover	54.7%	12	-10.0%	0
Low turnover	0.0%	0	—	0
Unknown	6.2%	2	-0.5%	0

Holding horizon	Share	Filers	Change	New
Short horizon	71.7%	15	-5.9%	1
Long horizon	14.7%	4	+5.1%	0
Unknown	13.5%	6	-1.6%	0

13F book size	Share	Filers	Change	New
Under $1B	35.8%	7	-0.5%	0
$1B to $10B	43.0%	11	-9.5%	1
$10B to $100B	17.5%	4	+4.1%	0
$100B or more	3.7%	3	0.0%	0

Client base	Share	Filers	Change	New
Pooled investment vehicles	62.5%	13	-8.2%	0
Registered funds and BDCs	8.0%	2	+23.6%	1
Unknown	29.4%	10	+0.1%	0

Private funds	Share	Filers	Change	New
Hedge funds	70.9%	15	-7.3%	0
No private funds	1.5%	1	new	1
Unknown	27.5%	9	+0.2%	0

Location	Share	Filers	Change	New	Exited
United States	76.1%	20	-5.8%	1	0
Outside the US	23.9%	5	+3.1%	0	0

How the mix is measured

Shares are 13F common shares restated to today's split basis; options and principal amounts are left out. The change compares only filers with a 13F in both quarters and keeps each filer in its bucket of the later quarter on both sides; a filer that continues under a new CIK is compared through its successor. Holder type comes from each filer's current regulatory profile; client base and private funds come from the Form ADV roster current at each quarter end (rosters from December 2019, so an earlier quarter reads Unknown). Style, turnover, horizon and book size are measured from each filer's 13F book in the newest measured quarter, and Not measured means none was. Actively managed books are those measured systematic-like, concentrated or diversified active.

Conviction and Crowding

25 13F filers, quarter ended Jun 30, 2026

Measured across every 13F filer's common-share book once the quarter's filing window closed. Crowding counts filers with high turnover or that advise private funds on Form ADV.

Conviction holders

0.000% of filers hold it in their top 10

Mar 31, 2026: 0

Holders above 5%

median weight 0.001%

Mar 31, 2026: 0

Crowding

—

shares outstanding is an issuer-wide count, not one listing's

Private-fund advisers

—

of shares outstanding

Institutional ownership

—

shares outstanding is an issuer-wide count, not one listing's

Top 10 holders

72.9%

of 13F shares, Herfindahl 0.069

Active holders

-3.8%

like-for-like share change of active filers

5% stakes on record

0 13D, 0 13G

How long holders have held it value-weighted 3.2 quarters

Under 1 year 62.4% 1 to 3 years 37.6% 3 years or more 0.000% Since coverage start 0.000%

Managers in the top fifth by current three-year FundScore alpha were net buyers of $0 (0 buying, 0 selling).

Shared Holders

Companies QUMSR's active holders also own, quarter ended Jun 30, 2026

#	Company	Shared holders	Similarity
1	XFLH XFLH Capital Corp	9	0.671
2	NMP NMP Acquisition Corp.	8	0.667
3	FVN Future Vision II Acquisition Corp.	6	0.655
4	CRAC Crown Reserve Acquisition Corp. I	8	0.617
5	QSEA Quartzsea Acquisition Corp	6	0.612
6	DMAA Drugs Made In America Acquisition Corp.	7	0.609
7	XRPNU Armada Acquisition Corp. II	10	0.602
8	FSHP Flag Ship Acquisition Corp	5	0.589
9	WENC West Enclave Merger Corp.	5	0.589
10	UYSC UY Scuti Acquisition Corp.	4	0.577

Shareholder Targets

13F filers that own its peers but not QUMSR, quarter ended Jun 30, 2026

Found through its holder-overlap peers: XFLH, NMP, FVN, CRAC, QSEA, DMAA, XRPNU, FSHP, WENC, UYSC, MYX, AIIA, SAGU, XSLL, OHAC, BREZ, APAC, TRAD, ARCL, KFII. 89 filers in all.

#	Filer	In peers	Of book	Largest peers
1	Magnetar Financial LLC Registered adviser, Concentrated	$81,255,859 9 held	0.800%	CRAC, KFII, BREZ
2	ARISTEIA CAPITAL, L.L.C. Registered adviser, Diversified active	$72,327,297 14 held	2.49%	XSLL, ARCL, OHAC
3	Arrington Capital Management, LLC Registered adviser, Concentrated	$60,513,320 1 held	67.1%	XRPNU
4	TENOR CAPITAL MANAGEMENT Co., L.P. Registered adviser, Diversified active	$47,939,874 4 held	3.02%	XRPNU, KFII, XSLL
5	MANGROVE PARTNERS IM, LLC Registered adviser, Diversified active	$37,459,672 12 held	2.52%	ARCL, BREZ, KFII
6	WHITEBOX ADVISORS LLC Registered adviser, Diversified active	$35,439,976 11 held	1.78%	MYX, ARCL, SAGU
7	TWO SIGMA INVESTMENTS, LP Registered adviser, Systematic-like	$35,018,525 13 held	0.030%	KFII, XSLL, NMP
8	METEORA CAPITAL, LLC Adviser, Diversified active	$34,935,667 11 held	3.19%	XRPNU, BREZ, KFII
9	LMR Partners LLP Exempt adviser, Diversified active	$31,812,748 7 held	0.280%	XRPNU, KFII, CRAC
10	SONA ASSET MANAGEMENT (US) LLC Registered adviser, Diversified active	$25,490,731 8 held	1.16%	OHAC, AIIA, XSLL

Quarterly Activity

vs Mar 31, 2026

New

Increased

Decreased

Sold Out

Unchanged

New and Sold Out count only filers that reported a 13F for both quarters: a first-time filer's book is not a buy, and a fund that has not filed, or withheld its positions under confidential treatment, has not sold.

Holder count: +1

Institutional value: -28.8%

Shares held: -3.8%

Top Buyers

vs Mar 31, 2026

Institution	Added	Now Holds
Large TORONTO DOMINION BANK	+47,068	717,905
Mid Shaolin Capital Management LLC	+19,379	479,379
Mid AQR Arbitrage LLC	+3,246	324,248

Top Sellers

vs Mar 31, 2026

Institution	Sold	Now Holds
Mid HIGHBRIDGE CAPITAL MANAGEMENT LLC	−383,088	307,316
Small HEIGHTS CAPITAL MANAGEMENT, INC	−31,213	106,968
Mid BERKLEY W R CORP	−11,002	24,108
Mid WOLVERINE ASSET MANAGEMENT LLC	−2,661	132,552
Large Clear Street Group Inc.	−2,000	222,380

Top New Positions

vs Mar 31, 2026

Institution	Acquired	Value (USD)	Open
Mid Westchester Capital Management, LLC	100,000	$12,250

Top Sold-Out Positions

vs Mar 31, 2026

No fully closed positions this quarter.

Filter: New 1 Increased 3 Reduced 6 Sold out 0 Unchanged 15

Holder type: Registered adviser 15 Exempt adviser 1 Bank 2 Insurer 1 Non-US 2 Unknown 4

Showing 25 of 25

All Common Calls Puts

Compact Export CSV

Holder

Value (USD)

% of 13F

Harraden Circle Investments, LLC QUMSR

$197,791

17.76%

993,926

TORONTO DOMINION BANK QUMSR

$142,863

12.83%

717,905

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
TD SECURITIES (USA) LLC	717,905	$142,863	100.0%	Defined

Shaolin Capital Management LLC QUMSR

$95,396

8.57%

479,379

RIVERNORTH CAPITAL MANAGEMENT, LLC QUMSR

$65,842

5.91%

424,512

AQR Arbitrage LLC QUMSR

$64,525

5.79%

324,248

Polar Asset Management Partners Inc. QUMSR

$64,280

5.77%

400,000

Linden Advisors LP QUMSR

$64,280

5.77%

400,000

HGC Investment Management Inc. QUMSR

$59,700

5.36%

300,000

HIGHBRIDGE CAPITAL MANAGEMENT LLC QUMSR

$52,244

4.69%

307,316

Clear Street Group Inc. QUMSR

$44,254

3.97%

222,380

Cable Car Capital, LP QUMSR

$34,785

3.12%

174,801

RLH Capital LLC QUMSR

$29,713

2.67%

184,900

WOLVERINE ASSET MANAGEMENT LLC QUMSR

$26,378

2.37%

132,552

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Wolverine Holdings, LLC	132,552	$26,378	100.0%	Defined

Hudson Bay Capital Management LP QUMSR

$25,500

2.29%

150,000

Radcliffe Capital Management, L.P. QUMSR

$24,105

2.16%

150,000

HEIGHTS CAPITAL MANAGEMENT, INC QUMSR

$21,287

1.91%

106,968

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
CVI Investments, Inc.	106,968	$21,287	100.0%	Other

D. E. Shaw & Co., Inc. QUMSR

$21,250

1.91%

125,000

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
D. E. SHAW & CO, L.P.	125,000	$21,250	100.0%	Defined

Periscope Capital Inc. QUMSR

$20,088

1.80%

125,000

BNP PARIBAS ARBITRAGE, SA QUMSR

$16,374

1.47%

102,340

BOOTHBAY FUND MANAGEMENT, LLC QUMSR

$16,070

1.44%

100,000

Westchester Capital Management, LLC QUMSR

$12,250

1.10%

100,000

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
WESTCHESTER CAPITAL PARTNERS, LLC	937	$114	0.9%	Sole
Virtus Investment Advisers, LLC	90,801	$11,123	90.8%	Other
Held directly	8,262	$1,012	8.3%	Sole

Schonfeld Strategic Advisors LLC QUMSR

$8,709

0.78%

54,200

BERKLEY W R CORP QUMSR

$3,874

0.35%

24,108

UBS Group AG QUMSR

$1,955

0.18%

16,027

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
UBS Securities LLC	16,027	$1,955	100.0%	Defined

GLAZER CAPITAL, LLC QUMSR

$68

0.01%

420,536

Key facts CIK 2070900 CUSIP G7387B106