- OBAM Investment Management BV
- OBP Capital, LLC
- Obra Fund Management, LLC
- Ocean Park Asset Management, LLC
- ODDO BHF Asset Management GmbH
- ODDO BHF Asset Management Lux
- ODDO BHF Asset Management SAS
- Odey Asset Management LLP
- OFI Asset Management
- Ökoworld Lux S.A.
- One Capital Management, LLC
- One Fund Management SA
- OneAscent Investment Solutions, LLC
- Optigestion Europe
- OPTINOVA Investment AG
- Orbis Investment Management (Luxembourg) SA
- Osprey
- Ossiam
- OTP invest d.o.o.
- Otter Creek Advisors, LLC
