Top 10 largest insurers in the large group, small group and individual markets

Kaiser Permanente is the largest insurer by enrollment in the fully insured large group market, UnitedHealth Group is the largest within the fully insured small group market, and Centene is the largest within the individual market, according to the Peterson-KFF health system tracker.

The following rankings show the 10 largest health insurers by enrollment in 2023 in each of three market segments: fully insured large group, fully insured small group and individual. The data comes from Mark Farrah Associates using HHS Medical Loss Ratio filings, with enrollment measured in life-years and individual insurers aggregated to the parent company level.

The group market rankings exclude self-funded plans, which now cover about two-thirds of workers with employer-sponsored insurance. Between 2013 and 2023, enrollment in fully insured large group plans fell from about 46 million to 38 million, while fully insured small group enrollment dropped from 17 million to 10 million, reflecting a broader shift toward self-funded arrangements. Individual market enrollment, meanwhile, grew from 11 million to 18 million, driven largely by the ACA marketplaces and enhanced premium subsidies.

Largest insurers in the fully insured large group market:

1. Kaiser Permanente: 7 million members
2. UnitedHealth Group: 4.7 million
3. Elevance Health: 3.4 million
4. Health Care Service Corp: 3.1 million
5. CVS Health: 2.3 million
6. Cigna Healthcare: 2 million
7. Blue Shield of California: 1.1 million
8. BCBS Michigan: 982,000
9. GuideWell: 912,000
10. Highmark: 896,000

Largest insurers in the fully insured small group market:

1. UnitedHealth Group: 1.6 million
2. Health Care Service Corp: 1.2 million
3. Kaiser Permanente: 979,000
4. Elevance Health: 932,000
5. Blue Shield of California: 485,000
6. CareFirst BCBS: 318,000
7. BCBS Michigan: 305,000
8. GuideWell: 246,000
9. Cambia Health Solutions: 224,000
10. Highmark: 190,000

Largest insurers in the individual market:

1. Centene: 3.3 million
2. GuideWell: 1.5 million
3. Health Care Service Corp: 1.2 million
4. CVS Health: 1.1 million
5. Kaiser Permanente: 1.1 million
6. Oscar Health: 909,000
7. Elevance Health: 872,000
8. Cigna Healthcare: 830,000
9. Blue Shield of California: 769,000
10. UnitedHealth Group: 706,000