Market concentration in private health insurance generally higher in 2024 than 2011, GAO finds

The Government Accountability Office found that enrollment in private health insurance plans remained concentrated in 2024, with a small number of issuers enrolling most people in a given market. The agency considers a market concentrated if three or fewer issuers hold at least 80 percent of enrollment share.

GAO examined the individual, small-group, and large-group health insurance markets from 2011 through 2024 across states. The number of states with concentrated markets generally increased over this period, with recent decreases observed in the individual market.

The agency also examined individual insurance exchanges, which are marketplaces where consumers can compare and select among insurance plans. The number of states where individual exchanges were concentrated increased from 47 states in 2015 to a peak of 51 states in 2020 and then decreased to 49 states in 2024.

GAO determined market share using enrollment data from 2011 through 2024 that issuers reported to the Centers for Medicare and Medicaid Services. The agency also used enrollment data that it collected from individual states from 2015 to 2017.

This report is the seventh in a series that GAO produces periodically as required by the Patient Protection and Affordable Care Act. GAO provided a draft of the report to the Department of Health and Human Services. The department provided technical comments that GAO incorporated as appropriate.