A new analysis examines how market concentration among commercial health insurers has shifted across the large group, small group, and individual markets from 2013 to 2023. The review uses enrollment data for fully insured and individual plans from Mark Farah Associates, along with data for self-funded plans for selected charts. It evaluates market competition through three measures. These include the market share of each state’s largest insurer, the number of insurers within a state that hold at least 5 percent market share, and the Herfindahl-Hirschman Index, which is a widely used metric to assess market concentration across industries.
Regulation and the market power of other healthcare stakeholders influence how consolidation affects prices and enrollee experience. High concentration may give insurers more leverage to negotiate lower payments to providers. However, limited competition may reduce incentives to lower enrollee costs and may restrict the choices available to purchasers.
Although insurer participation often varies within states, the analysis focuses on state-level data and national averages. These figures illustrate broad trends in competitiveness, but they may not fully reflect the local markets where consumers access coverage. Group market plans may cover employees who live across the country, while individual market plans often apply at the county or local level. In many cases, insurers do operate statewide.
Across commercial health insurance markets, concentration remained high between 2013 and 2023. However, the individual market became more competitive after 2020, while fully insured group markets became less competitive. Most people who purchase individual market coverage do so through the Affordable Care Act Marketplaces. Coverage purchased through the Marketplace often complies with ACA standards, which means it generally aligns with the designs of Marketplace plans.
Enrollment Dominance Among the Largest U.S. Parent Companies
The analysis also highlights that a small number of health insurers account for most enrollment in several major coverage categories. These include fully insured and self-funded private insurance, Medicaid Managed Care, Fee-for-Service type Medicaid programs, and Medicare Advantage. As of 2025, UnitedHealth, Elevance Health, and CVS Health are the three largest parent companies in the United States. Insurers often specialize in different markets. For example, most of Centene’s medical membership participates in Medicaid, while most of UnitedHealth’s medical membership participates in commercial insurance.
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