- OneCare
- OnShift
- OpenPlacement
- Oppenheimer & Co.
- Opportunity Lives
- Optima Health
- Optima Health Plan
- Optima Healthcare
- Optima Healthcare Solutions
- Optimal Care Inc.
- Optimal Home Care
- Option Care
- Option Care Health
- Option Health Care
- Options Home Care
- Optum
- Optum Healthcare
- Optum Public Sector Solutions
- Optum Ventures
- OptumCare