Ticker · CUSIP 74765K105

QSI

QUANTUM SI INC
···Share
Holders (tracked)
8
Combined shares
12,273,815
Combined value
$13.40M
Last close
$1.04
Quarter
2025Q4
Tracked holders · last 8 quarters
Flat over the last 8 quarters.
882024Q12025Q4
Price is -4.7% vs the avg quarter-end implied price across tracked holders.

SEC event timeline

12 events
  1. +2,269,050 shares · 2025Q4
    13F
  2. −2,478,168 shares · 2025Q4
    13F
  3. +4,452 shares · 2025Q4
    13F
  4. +2,865 shares · 2025Q4
    13F
  5. +868,329 shares · 2025Q4
    13F
  6. −602,471 shares · 2025Q4
    13F
  7. −37,879 shares · 2025Q3
    13F
  8. −1,109,300 shares · 2025Q3
    13F
  9. −48,590 shares · 2025Q3
    13F
  10. −28,472 shares · 2025Q3
    13F
  11. −89,200 shares · 2025Q3
    13F
  12. −336,694 shares · 2025Q3
    13F

Insider activity

No insider transactions in the last 30 days.
Follow-the-investor returns
If you'd copied each holder of QSI…
Cost basis inferred from 13F share-delta history. Sorted by % return on the position they're still holding.
InvestorFirst inCost basisReturnPosition value today
Ken Griffin (Citadel Advisors)2021Q2$1.16-10.2%$578K
Ken Griffin (Citadel Advisors)2021Q2$1.16-10.2%$578K
Ken Griffin (Citadel Advisors)2021Q2$1.16-10.2%$578K
Two Sigma Investments2022Q4$1.21-13.8%$1.4M
Izzy Englander (Millennium Mgmt)2021Q2$1.21-14.2%$199K
AQR Capital Management2022Q1$2.55-59.3%$90K
T. Rowe Price2021Q2$3.47-70.0%$100K
Cathie Wood (ARK Invest)2021Q2$7.41-86.0%$7.3M

Who moved on this name in 2025Q4

13F transactions reported for the latest quarter, grouped by direction.
New positions0
Trimmed2
Exited0

Institutional ownership over time

Distinct super-investors holding this ticker · combined dollar value, by quarter.
QuarterHoldersCombined value
2022Q1
10
$106.6M
2022Q2
9
$87.1M
2022Q3
8
$69K
2022Q4
11
$42.3M
2023Q1
12
$39.2M
2023Q2
10
$40.3M
2023Q3
6
$36.2M
2023Q4
7
$46.8M
2024Q1
8
$40.4M
2024Q2
9
$21.2M
2024Q3
9
$10.8M
2024Q4
7
$28.9M
2025Q1
9
$18.5M
2025Q2
9
$27.1M
2025Q3
8
$17.0M
2025Q4
8
$13.4M

Who owns QSI

8 super-investors · 2025Q4
Tracked stake
12.27M
shares
Combined value
$13M
% of shares outstanding
shares-out unknown
Quarter action mix
Added6Trim2
#ManagerSharesValue
1Cathie Wood
ARK Invest
7.02M$8M
2Ken Griffin
Citadel Advisors
2.68M$3M
3Two Sigma Investments1.38M$2M
4Ken Griffin
Citadel Advisors
556.0K$612K
5Ken Griffin
Citadel Advisors
261.0K$287K
6Izzy Englander
Millennium Mgmt
191.8K$211K
7AQR Capital Management86.7K$95K
8T. Rowe Price96.5K$107

Recent moves

20 transactions
Embed this chart
Paste this iframe anywhere to embed the live QSI chart.
<iframe src="https://openstocks.me/embed/stock/QSI" width="100%" height="480" frameborder="0" loading="lazy" title="QSI chart by OpenStocks" style="border:0;border-radius:12px;background:transparent"></iframe>