11 institutions reported holding $1.4M of QUANTUM SI INC (QSIAW) in SEC 13F filings for 2026-06-30. Largest institutional holders: GROUP ONE TRADING LLC ($605,162), IMC-Chicago, LLC ($410,640), SIMPLEX TRADING, LLC ($338,246), AlphaCore Capital LLC ($4,063), WOLVERINE ASSET MANAGEMENT LLC ($0). Source: SEC Form 13F.
| Rank | Institution | Value | Shares | Change |
|---|---|---|---|---|
| 1 | GROUP ONE TRADING LLC | $605,162 | 683,800 | Added |
| 2 | IMC-Chicago, LLC | $410,640 | 464,000 | Added |
| 3 | SIMPLEX TRADING, LLC | $338,246 | 382,200 | Added |
| 4 | AlphaCore Capital LLC | $4,063 | 125 | New |
| 5 | WOLVERINE ASSET MANAGEMENT LLC | $0 | 0 | Exited |
| 6 | SUSQUEHANNA INTERNATIONAL GROUP, LLP | $0 | 0 | Exited |
| 7 | DEERFIELD MANAGEMENT COMPANY, L.P. | $0 | 0 | Exited |
| 8 | JANE STREET GROUP, LLC | $0 | 0 | Exited |
| 9 | UBS Group AG | $0 | 0 | Exited |
| 10 | TORONTO DOMINION BANK | $0 | 0 | Exited |
| 11 | MILLENNIUM MANAGEMENT LLC | $0 | 0 | Exited |
Source: SEC Form 13F filings · as of 2026-06-30