3 institutions reported holding $39.0M of WATSCO INC (WSO.B) in SEC 13F filings for 2026-06-30. Largest institutional holders: GROUP ONE TRADING LLC ($29.2M), IMC-Chicago, LLC ($9.8M), SIMPLEX TRADING, LLC ($83,346). Source: SEC Form 13F.
| Rank | Institution | Value | Shares | Change |
|---|---|---|---|---|
| 1 | GROUP ONE TRADING LLC | $29.2M | 70,000 | Hold |
| 2 | IMC-Chicago, LLC | $9.8M | 23,400 | Trimmed |
| 3 | SIMPLEX TRADING, LLC | $83,346 | 200 | Trimmed |
Source: SEC Form 13F filings · as of 2026-06-30