Largest major medical insurance provider by state
Individual health insurance policies can be purchased through the health insurance marketplace if you currently do not receive health care through an employer or a federally funded program like Medicaid or Medicare. In 2021, 13.6 million people enrolled in plans through the health insurance marketplace.

Based on our analysis, UnitedHealthcare is the largest health insurance company by revenue, with total revenue topping $286 billion for 2021. This makes the insurer the largest company by membership, market share and revenue. Anthem is the second-largest health care company in all three categories.

Health insurance companies create revenue through premiums, policy volume, the services they sell and the number of businesses they operate in.

Top 5 largest health insurance companies by membership

1. UnitedHealth Group

UnitedHealthcare, part of UnitedHealth Group, is the largest health insurance company by total members. UnitedHealthcare offers a variety of products from individual health insurance to full employer benefit plans for some of the biggest corporations. Furthermore, its policies can be purchased in all 50 states. UnitedHealthcare is headquartered in Minnetonka, Minn.

Along with having the most members, UnitedHealthcare also has a network of over 1.3 million physicians and health care professionals, with more than 6,500 hospitals. This means that if you have UnitedHealthcare, you will have many options to choose from to receive care.

2. Anthem

Anthem is the second-largest medical insurance provider by total members, with more than 45 million members. The company's Commercial and Business health care segment offers network-based care to large and small businesses, individuals and Medicaid and Medicare markets.

Anthem is part of the Blue Cross Blue Shield Association. This means that when searching for Anthem policies on your state marketplace exchange, you may find products with the BCBS name, but you will be buying from Anthem.

The company currently operates in California, Colorado, Connecticut, Georgia, Indiana, Kentucky, Maine, Missouri, Nevada, New Hampshire, New York, Ohio, Virginia and Wisconsin.

3. Aetna

Aetna was acquired by CVS Health Corp. in 2018. CVS Health now operates the company and has been able to seamlessly integrate its provider networks with Aetna's membership base. Founded in 1853, Aetna is the third-largest provider of health insurance and services, by membership. However, much of its membership comes from providing health insurance to employers and their employees in the private market. Aetna returned to a limited number of ACA marketplaces for the 2022 plan year.

4. Cigna

Cigna is the fourth-largest major medical insurance company in the United States. Headquartered in Bloomfield, Conn., Cigna offers health insurance and health services to companies throughout the world. In addition to corporate health insurance policies and management of those plans, Cigna also offers dental, behavioral health, vision, supplemental health and Medicare/Medicaid benefits.

Cigna currently offers individual health insurance in 13 states: Arizona, Colorado, Florida, Georgia, Illinois, Kansas, Mississippi, Missouri, North Carolina, Pennsylvania, Tennessee, Utah and Virginia. Cigna also provides Medicare Advantage plans in 16 states and Washington, D.C.

5. Humana

Humana comes in as the fifth-largest health insurance company by membership. The provider was founded in 1961 and originally sold long-term care insurance before expanding into selling health insurance policies. Humana has not offered new individual ACA health insurance since January 2018 but will continue to honor its existing ACA policies. Humana is now focused on serving the Medicare market, with either a Medicare Advantage or a supplemental plan (or both) available in every state.