QUANTUM-SI INC (QSI) Institutional Selling Activity
Several institutional investors tracked by InsiderSet reduced exposure to QUANTUM-SI INC (QSI) during the quarter ended March 31, 2026 based on sequential SEC Form 13F filings.
The largest disclosed institutional seller of QSI during the latest reporting period reduced its reported position by approximately $8.08M based on quarter-end filing values.
Institutional selling activity may reflect profit-taking, sector rotation, portfolio rebalancing, or changing conviction levels among major investment firms. InsiderSet tracks quarter-over-quarter holding reductions, full exits, estimated value changes, and historical selling activity using publicly disclosed SEC filing data.
The investors covered on this page collectively reduced approximately $21.77M in reported QSI exposure during the latest filing period, although many institutional holders continue to maintain significant long-term ownership positions in QUANTUM-SI INC.
| Portfolio quarter | Name | Type | Quantity | Remaining | Reported stock balance |
|---|---|---|---|---|---|
| Q1 2026 | ARK Invest | Sell | -142,672 | 6,878,899 | $5,324,268 |
| Q4 2025 | ARK Invest | Sell | -602,471 | 7,021,571 | $7,723,728 |
| Q3 2025 | ARK Invest | Sell | -336,694 | 7,624,042 | $10,749,899 |
| Q2 2025 | Renaissance Technologies LLC | Sell | -782,556 | 89,200 | $174,832 |
| Q2 2025 | ARK Invest | Sell | -752,765 | 7,960,736 | $15,603,043 |
| Q1 2025 | ARK Invest | Sell | -135,149 | 8,713,501 | $10,456,201 |
| Q4 2024 | ARK Invest | Sell | -2,993,959 | 8,848,650 | $23,891,355 |
| Q3 2024 | ARK Invest | Sell | -567,320 | 11,842,609 | $10,447,550 |
| Q3 2024 | Renaissance Technologies LLC | Sell | -181,700 | 41,556 | $36,661 |
| Q2 2024 | ARK Invest | Sell | -358,947 | 12,409,929 | $13,030,425 |
| Q1 2024 | ARK Invest | Sell | -2,750,446 | 12,768,876 | $25,154,686 |
| Q1 2023 | ARK Invest | Sell | -157,393 | 11,698,791 | $20,589,872 |
| Q4 2022 | ARK Invest | Sell | -1,381,606 | 11,856,184 | $21,696,817 |
| Q3 2022 | ARK Invest | Sell | -631,294 | 13,237,790 | $36,404 |
Frequently asked questions about QSI activity
Which institutional owners are buying QSI?
Institutional owners buying QSI include investors who have either initiated new positions or increased their existing holdings based on recent SEC 13F filings. The activity table above highlights which funds added shares in the latest reporting periods and how their positions changed over time.
What does "buy" mean in QSI activity?
"Buy" means an investor increased their reported position in QSI compared to the prior reporting period. This reflects growing exposure to QUANTUM-SI INC (QSI) rather than necessarily a brand-new position (though new positions also appear as buys when prior quantity was zero).
Is institutional interest in QSI increasing?
Institutional interest in QSI can be assessed by comparing the number of tracked funds adding or increasing positions versus those trimming or exiting across the periods shown. A higher number of additions typically signals increasing participation among large filers, but it should be read alongside position sizes and the full table.