238 institutions reported holding $437.6M of OIL STS INTL INC (OIS) in SEC 13F filings for 2026-06-30. Largest institutional holders: BlackRock, Inc. ($54.6M), VANGUARD GROUP INC ($36.7M), DIMENSIONAL FUND ADVISORS LP ($24.1M), AMERICAN CENTURY COMPANIES INC ($17.7M), ACADIAN ASSET MANAGEMENT LLC ($16.4M). Source: SEC Form 13F.
Source: SEC Form 13F filings · as of 2026-06-30