The U.S. commercial health insurance market has remained highly concentrated from 2013 to 2023, though recent years have seen divergent trends across market segments. A recent report shared by Peterson-KFF used enrollment data for fully insured and individual plans to assess market competition.
The data shows that overall, large and small group markets — where employers purchase fully insured coverage — have become less competitive, while the individual market has grown more competitive since about 2020.
According to the report, enrollment in fully insured large group plans dropped from roughly 46 million in 2013 to about 38 million in 2023, and small group enrollment fell from around 17 million to 10 million. In contrast, individual market enrollment increased from about 11 million to 18 million over that period, in part due to the Affordable Care Act’s Marketplace and enhanced premium tax credits introduced in 2021.
At the same time, self-funded group plans — where employers assume financial responsibility for claims — grew from about 110 million to roughly 127 million enrollees. Employers, especially larger ones, increasingly prefer these self-funded options. The report found that in 2025, 67% of covered workers were enrolled in a self-funded plan. Whereas, small employers are increasingly shifting towards level-funded plans due to rising premiums in the fully insured small group market.
Additionally notable, the report found that market concentration varies widely by state and segment. Some states have dominant insurers with very high market shares, while others display more balanced competition.
“Aside from the few insurers with a large presence across the country, most insurers specialize in just one or a handful of states, leaving many local insurance markets with a few dominant insurers,” the report said.
For example, Guidewell, the second-largest insurer in the individual market, only operates in Florida. While Guidewell has 8% market share nationally, in the individual market, it represents a plurality of Florida’s individual market enrollment of 43%.
At the extreme, within the individual market, Highmark has 93% market share in Delaware, while Wellmark has 90% share in Iowa.
Despite modest gains in individual market competition, many Americans still live in states where one or two insurers dominate coverage options, shaping access, pricing, and plan availability across much of the commercial market.
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