The American Medical Association (AMA) published its annual edition of Competition in Health Insurance: A Comprehensive Study of U.S. Markets showing the rise of highly concentrated markets for health insurance.

The updated study analyzed market concentration and health insurer market shares for 384 metropolitan statistical areas (MSAs), the 50 states and the District of Columbia. For the first time, the study presented national-level market shares for the 10 largest health insurers in the United States. The study’s findings show most health insurance markets in the United States are highly concentrated leaving millions of Americans with more limited health insurer options, the AMA said.

“As merger rumors involving health insurers swirl, the prospect of future consolidation in the health insurance industry should be more closely scrutinized given the low levels of competition in most health insurance markets,” said AMA President Gerald E. Harmon, MD, who recently spoke at CAP21. “For two decades, the AMA study has been helping researchers, lawmakers, policymakers, and federal and state regulators identify markets where consolidation involving health insurers may cause competitive harm to consumers and providers of care.”

The AMA’s latest study of competition in commercial health insurance markets shows:

• 73%, or 280, of MSA-level markets were high concentrated according to federal guidelines.
• 46%, or 178, of MSA-level markets had one insurer with a share of 50% or more.
• Between 2014 and 2020, the share of highly concentrated markets rose from 71% to 73%.
• 54% of markets that were already highly concentrated in 2014 became even more concentrated by 2020.
• The health insurers with the highest market share in the most MSA-level markets were: 1. Anthem (80 MSAs), 2. Health Care Service Corp. (44 MSAs), 3. UnitedHealth Group and Blue Cross Blue Shield of Florida (each with 22 MSAs apiece), and 4. Highmark and Kaiser (each with 20 MSAs apiece).
• The 10 states with the least competitive commercial health insurance markets were: 1. Alabama, 2. Michigan, 3. Louisiana, 4. South Carolina, 5. Hawaii, 6. Kentucky, 7. Alaska, 8. Illinois, 9. North Dakota, and 10. Oklahoma.
• The 10 largest health insurers in the United States at the national-level by market share were: 1. UnitedHealth Group (15%), 2. Anthem (12%), 3. Aetna (11%), 4. Cigna (10%), 5. Kaiser (7%), 6. Health Care Service Corp. (6%), 7. Blue Cross Blue Shield of Michigan (2%), 8. Blue Cross Blue Shield of Florida (2%), 9. Blue Shield of California (2%), and 10. Centene (2%).