SummaryBy revenue, UnitedHealth Group is the nation's largest publicly traded managed care company. It operates through two business segments, UnitedHealthcare and Optum. UnitedHealthcare provides healthcare benefits through four membership groups: Employers & Individual, Medicare & Retirement, Community & State, and International. The Optum segment is a health services business that serves payers, care providers, employers, governments, life science companies, and consumers. Its OptumHealth business provides care delivery in primary and specialty care, care management, and wellness programs.