Earlier this week, the American Medical Association (AMA) released publication of the 2024 Update to Competition in Health Insurance: A Comprehensive Study of U.S. Markets, which is based on data from 2023. 

The 2024 Update to Competition in Health Insurance includes the two largest insurers’ market shares and the Herfindahl-Hirschman Indices (HHIs)—a measure of market concentration—for 382 metropolitan statistical areas (MSAs), the 50 states including Ohio, and the District of Columbia. It finds that the vast majority of health insurance markets remain stubbornly highly concentrated and at risk for insurer mergers to substantially lessen competition.

Key findings include:

Commercial markets

• 95% (364) of MSA-level markets were highly concentrated (HHI>1,800) in 2023—the same proportion as in 2014.
• The average HHI across MSA-level markets was 3458 in 2023.
• In 89% (339) of MSAs, at least one insurer held a commercial market share of 30% or greater, and in 47% (181) of MSAs, one insurer's share was at least 50%.
• A Blue Cross Blue Shield (BCBS) insurer had the largest state-level market share in 41 states and in 83% (317) of MSAs.
• Elevance Health (a BCBS insurer) had the largest MSA-level market share in 21% (80) of MSAs.
• At the national level, UnitedHealth Group was the largest commercial health insurer in the U.S. and Centene was the largest insurer in the exchanges.

 Medicare Advantage (MA) markets

• Ninety-seven percent (372) of MSA-level markets were highly concentrated (HHI>1,800) in 2023—down from 99% in 2017.
• The average HHI across MSA-level markets was 3129 in 2023.
• In 91% (347) of MSAs, at least one insurer held a market share of 30% or greater and in 30% (116) of MSAs, one insurer's share was at least 50%.
• UnitedHealth Group had the largest MSA-level market share in 43% (165) of MSAs, and Humana was the biggest in 22% (84) of MSAs.
• At the national level, UnitedHealth Group is the largest health insurer in the U.S.

Read the Full 2024 Update >