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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Market Share of Largest Insurers
| wdt_ID | wdt_created_by | wdt_created_at | wdt_last_edited_by | wdt_last_edited_at | State | Top Insurer (2024) | Market Share |
|---|---|---|---|---|---|---|---|
| 1 | Patience | 21/09/2026 03:48 PM | Patience | 21/09/2026 03:48 PM | Alabama | BCBS of Alabama | 95% |
| 2 | Patience | 21/09/2026 03:48 PM | Patience | 21/09/2026 03:48 PM | Alaska | Premera Blue Cross | 94% |
| 3 | Patience | 21/09/2026 03:48 PM | Patience | 21/09/2026 03:48 PM | Arizona | BCBS of Arizona | 60% |
| 4 | Patience | 21/09/2026 03:48 PM | Patience | 21/09/2026 03:48 PM | Arkansas | Arkansas BCBS | 69% |
| 5 | Patience | 21/09/2026 03:48 PM | Patience | 21/09/2026 03:48 PM | California | Kaiser Permanente | 55% |
| 6 | Patience | 21/09/2026 03:48 PM | Patience | 21/09/2026 03:48 PM | Colorado | Kaiser Permanente | 61% |
| 7 | Patience | 21/09/2026 03:48 PM | Patience | 21/09/2026 03:48 PM | Connecticut | Elevance Health | 29% |
| 8 | Patience | 21/09/2026 03:48 PM | Patience | 21/09/2026 03:48 PM | Delaware | Highmark | 78% |
| 9 | Patience | 21/09/2026 03:48 PM | Patience | 21/09/2026 03:48 PM | District of Columbia | CVS Health (Aetna) | 32% |
| 10 | Patience | 21/09/2026 03:48 PM | Patience | 21/09/2026 03:48 PM | Florida | GuideWell Mutual Holding (BCBS of FL) | 46% |
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