What is the largest health insurance company in the United States by revenue?

UnitedHealth Group is the largest U.S. health insurance company by revenue. Its insurance business, UnitedHealthcare, is paired with the broader company’s Optum health-services businesses, making the parent group exceptionally large by total revenue.

UnitedHealthcare sells employer-sponsored, individual, Medicare, Medicaid, and military-related coverage. Optum operates in areas including health-care delivery, pharmacy services, and technology, so UnitedHealth Group’s consolidated revenue is not generated solely from insurance premiums. That distinction explains why some comparisons produce different rankings depending on whether they measure the parent company or only an insurance segment.

UnitedHealth Group grew from a health-plan company into a vertically integrated health-care enterprise through acquisitions and expansion. Its scale also means that “largest” can mean different things: revenue, enrollment, market capitalization, or number of covered members. Aetna, Cigna, and Anthem—now branded Elevance Health—are major competitors, but UnitedHealth Group remains the standard answer for revenue-based U.S. health-insurer trivia.