Consolidation in healthcare has reduced competition in several regions, including among health insurers.
The Kaiser Family Foundation used the Herfindahl-Hirschman Index to measure market share distribution among insurers with data from the California Department of Managed Healthcare and Health Coverage Portal. The report grouped all plans from a single parent company or insurer group in the analysis, and only plans with comprehensive major medical coverage were included.
The eight states where one insurer had at least 80 percent of the market share were:
1. Alabama: 94 percent
2. Alaska: 92 percent
3. South Carolina: 92 percent
4. Vermont: 90 percent
5. Wyoming: 86 percent
6. Mississippi: 84 percent
7. Montana: 83 percent
8. West Virginia: 80 percent