Health care insurance, in some ways, is not dissimilar to many other industries. With many options and disparate services in a variety of locations inevitably comes consolidation and market concentration, which ultimately decreases competition for consumers. That's according to new findings from a report by the American Medical Association called Competition in Health Insurance, A Comprehensive Study of U.S. Markets.

Key findings, using data from the Decision Resources Group, show that based on the Department of Justice/Federal Trade Commission Horizontal Merger Guidelines, 75% of metropolitan statistical areas (MSA)-level commercial markets are highly concentrated (Herfindahl-Hirschman Indices (HHI)>2500). The average commercial market is also highly concentrated, with an HHI of 3504. Other findings are that in 91% of MSA-level markets, at least one insurer has a commercial market share of 30% or greater, and in 48% of markets, a single insurer's share is at least 50%.