Where Data Tells the Story
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In the visualization above, 13 U.S. states have a single health insurer controlling more than 80% of the large-group market, which covers employer-sponsored plans for large companies.
This is based on numbers from KFF’s 2024 enrollment data.
Alabama has the highest concentration, with one insurer controlling 95% of the market, followed by Alaska at 94% and Wyoming at 91%. Concentration remains high in several other states, with Montana at 90%, South Carolina at 89%, and Iowa and North Carolina at 85%.
When a single insurer controls such a large share of the market, competitive pressure on premiums, provider networks, and coverage decisions can drop significantly. For many employers in these states, meaningful alternatives may be limited when choosing a health insurer.
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