3 institutions reported holding $1.3M of GLADSTONE INVT CORP (GAINN1) in SEC 13F filings for 2026-03-31. Largest institutional holders: SIMPLEX TRADING, LLC ($756,860), IMC-Chicago, LLC ($488,480), GROUP ONE TRADING LLC ($32,660). Source: SEC Form 13F.
| Rank | Institution | Value | Shares | Change |
|---|---|---|---|---|
| 1 | SIMPLEX TRADING, LLC | $756,860 | 53,300 | Added |
| 2 | IMC-Chicago, LLC | $488,480 | 34,400 | New |
| 3 | GROUP ONE TRADING LLC | $32,660 | 2,300 | New |
Source: SEC Form 13F filings · as of 2026-03-31