Quantum-si Inc: which funds bought and sold

Institutions that bought and sold Quantum-si shares in Q2 2026, from the holdings they reported to the SEC on Form 13F for March 31, 2026 and June 30, 2026.

Between March 31, 2026 and June 30, 2026, 63 institutions that filed 13F reports for both quarters added to or opened positions in Quantum-si, and 98 cut or closed them. Together they sold a net 10.1M shares, −16.0% on what they held at the start of the quarter. Active managers and hedge funds on our list were net buyers of 3.4M shares (+32.7%); index fund managers were net sellers of 14.5M shares (−44.3%). 28 opened a new position and 41 sold out entirely.

Bought, Q2 2026 63 institutions, 28 of them new holders Sold, Q2 2026 98 institutions, 41 of them sold out

Net change, all compared −10.1M shares (−16.0%)

Net change, active managers +3.4M shares (+32.7%), 11 bought, 11 sold

Buyers versus sellers

institutions compared, 182

63 bought 21 98 sold

Active managers and hedge funds 11 bought · 11 sold · +3.4M

Index fund managers 1 bought · 10 sold · −14.5M

Other institutions 51 bought · 77 sold · +978K

Biggest buyers

by change in shares held

Biggest buyers
Institution	Change in shares	Shares June 30, 2026	Value
Millennium Management LLC Hedge fund	+3.1M New position	3.1M	$2.8M
Jane Street Group, LLC	+2.1M New position	2.1M	$1.9M
UBS Group AG	+859K +50.5%	2.6M	$2.3M
Vanguard Capital Management LLC Index funds	+556K +7.9%	7.6M	$6.7M
Renaissance Technologies LLC Hedge fund	+436K +369.8%	554K	$490,176
BNP Paribas Financial Markets	+360K +938.3%	399K	$352,759
Aster Capital Management (Difc) Ltd	+345K New position	345K	$304,891
ARK Investment Management LLC Active manager	+289K +4.2%	7.2M	$6.3M
Morgan Stanley	+194K +148.9%	323K	$286,282
Barclays PLC	+167K +425.6%	206K	$182,035
HRT Financial LP	+94K New position	94K	$82,000
FMR LLC Active manager	+92K +287.2%	124K	$109,534
Y-Intercept (Hong Kong) Ltd	+79K New position	79K	$69,994
Winton Group Ltd Hedge fund	+76K New position	76K	$67,083
Simplex Trading, LLC	+75K +82.6%	165K	$146,284
Imc-Chicago, LLC	+65K +29.4%	286K	$252,896
Gsa Capital Partners LLP	+60K New position	60K	$53,000
Atom Investors LP	+52K New position	52K	$45,625
Jtc Employer Solutions Trustee Ltd	+43K +125.2%	78K	$69,000
Point72 Asset Management, L.P. Hedge fund	+39K New position	39K	$34,633

Biggest buyers, active managers and hedge funds
Institution	Change in shares	Shares June 30, 2026	Value
Millennium Management LLC Hedge fund	+3.1M New position	3.1M	$2.8M
Renaissance Technologies LLC Hedge fund	+436K +369.8%	554K	$490,176
ARK Investment Management LLC Active manager	+289K +4.2%	7.2M	$6.3M
FMR LLC Active manager	+92K +287.2%	124K	$109,534
Winton Group Ltd Hedge fund	+76K New position	76K	$67,083
Point72 Asset Management, L.P. Hedge fund	+39K New position	39K	$34,633
Citadel Advisors LLC Hedge fund	+29K +185.2%	44K	$39,236
Neuberger Berman Group LLC Active manager	+22K New position	22K	$19,263
Balyasny Asset Management L.P. Hedge fund	+14K New position	14K	$12,062
Laurion Capital Management LP Hedge fund	+13K New position	13K	$11,283

Biggest sellers

by change in shares held

Biggest sellers
Institution	Change in shares	Shares June 30, 2026	Value
Blackrock, Inc. Index funds	−8.2M −61.0%	5.2M	$4.6M
State Street Corp Index funds	−2.9M −76.4%	891K	$788,306
Geode Capital Management, LLC Index funds	−1.6M −41.7%	2.2M	$2M
Vanguard Portfolio Management LLC Index funds	−1.0M −67.3%	497K	$439,932
Northern Trust Corp Index funds	−810K −64.3%	451K	$398,720
Amova Asset Management Americas, Inc.	−506K −11.5%	3.9M	$3.5M
Sumitomo Mitsui Trust Group, Inc.	−506K −11.5%	3.9M	$3.4M
Nuveen, LLC	−421K −93.3%	30K	$26,619
Charles Schwab Investment Management Inc Index funds	−373K −81.5%	85K	$74,882
Bank Of New York Mellon Corp	−364K −95.1%	19K	$16,643
Susquehanna International Group, LLP	−348K −23.7%	1.1M	$988,324
Alliancebernstein L.P. Active manager	−272K Sold out	0	—
Xtx Topco Ltd	−212K −54.4%	178K	$157,247
CIBC Bancorp Usa Inc.	−209K Sold out	0	—
Group One Trading LLC	−177K −62.2%	107K	$95,114
Deutsche Bank Ag\	−119K Sold out	0	—
Rhumbline Advisers Index funds	−117K −60.6%	76K	$67,249
Los Angeles Capital Management LLC Active manager	−116K Sold out	0	—
Bank Of America Corp	−102K −63.2%	60K	$52,733
Metlife Investment Management, LLC	−102K Sold out	0	—

Biggest sellers, active managers and hedge funds
Institution	Change in shares	Shares June 30, 2026	Value
Alliancebernstein L.P. Active manager	−272K Sold out	0	—
Los Angeles Capital Management LLC Active manager	−116K Sold out	0	—
Price T Rowe Associates Inc Active manager	−96K Sold out	0	—
Quantbot Technologies LP Hedge fund	−58K Sold out	0	—
Bridgeway Capital Management, LLC Active manager	−55K −21.1%	206K	$182,399
Two Sigma Investments, LP Hedge fund	−53K Sold out	0	—
Intech Investment Management LLC Active manager	−46K Sold out	0	—
AQR Capital Management LLC Hedge fund	−44K −1.8%	2.3M	$2.1M
Graham Capital Management, L.P. Hedge fund	−12K Sold out	0	—
Walleye Capital LLC Hedge fund	−312 Sold out	0	—

New positions

largest by value

Institution	Shares	Value June 30, 2026
Millennium Management LLCHedge fund	3.1M	$2.8M
Jane Street Group, LLC	2.1M	$1.9M
Aster Capital Management (Difc) Ltd	345K	$304,891
HRT Financial LP	94K	$82,000
Y-Intercept (Hong Kong) Ltd	79K	$69,994
Winton Group LtdHedge fund	76K	$67,083
Gsa Capital Partners LLP	60K	$53,000
Atom Investors LP	52K	$45,625
Point72 Asset Management, L.P.Hedge fund	39K	$34,633
Corient Private Wealth LP	38K	$33,920

Sold out

largest by value

Institution	Shares	Value March 31, 2026
Alliancebernstein L.P.Active manager	272K	$299,398
CIBC Bancorp Usa Inc.	209K	$161,387
Deutsche Bank Ag\	119K	$91,652
Los Angeles Capital Management LLCActive manager	116K	$90,047
Metlife Investment Management, LLC	102K	$78,604
Price T Rowe Associates IncActive manager	96K	$75,000
Mirae Asset Global Etfs Holdings Ltd.	75K	$57,994
Virtu Financial LLC	65K	$50,000
Wells Fargo & Company	64K	$49,434
Quantbot Technologies LPHedge fund	58K	$45,249

Who holds the shares

13F holdings at June 30, 2026

Institutions reporting: 141
Ten largest holders: 75.9%
Index fund managers: 34.4%
Active managers and hedge funds: 26.0%

Buying and selling by type of institution, March 31, 2026 to June 30, 2026
Type	Bought	Sold	New	Sold out	Net change in shares	Net %
Active managers and hedge funds	11	11	7	8	+3.4M	+32.7%
Index fund managers	1	10	0	1	−14.5M	−44.3%
Other institutions	51	77	21	32	+978K	+4.9%

Active managers and hedge funds: a list we maintain of about 400 well-known stock-picking firms and hedge funds, matched by SEC registration number (CIK) and checked against the filer names each quarter. Index fund managers: the large index houses, such as BlackRock, Vanguard, State Street, Geode and Northern Trust. Every other filer (banks, brokers, wealth managers, pension funds, insurers and firms not on the list) counts as another institution. A firm that files under several SEC registrations appears once for each.

What these filings can and cannot tell you

Form 13F lists the long positions in US-listed shares held by investment managers with more than $100 million in such holdings. Managers file it up to 45 days after each quarter ends, so this page shows what funds held at the end of each quarter, not what they are doing now: a position may have changed since. Short positions, most derivatives and smaller managers are not included, and a cut can mean a fund lost clients or rebalanced rather than a view on Quantum-si.

Only managers that filed a holdings report for both quarters are compared (182 here). 2 other holders are left out: first-time or late filers, firms that changed their SEC registration, and filings that withheld positions under confidential treatment, any of which would otherwise look like a new position or a sale. Figures are as reported by each manager in the SEC's quarterly 13F data sets; option positions are excluded.

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