Anthem's proposed acquisition of Cigna and Aetna's proposed acquisition of Humana would collectively quash competition in insurance markets across 24 states, according to an updated analysis released today by the American Medical Association. The analysis is based on the association’s latest annual study of commercial health insurance markets, which found 71% of the markets are highly concentrated. In 40% of the 388 metropolitan areas studied, a single health insurer had at least a 50% share of the commercial health insurance market. In July, the Department of Justice sued to block the proposed acquisitions, which would create three major national insurers where there are now five. “The AHA has called for the DOJ to challenge the insurers mergers because of the impact they would have on costs and coverage for consumers,” said Melinda Hatton, AHA senior vice president and general counsel. “This analysis is just further evidence that the mergers would threaten competition in the insurance market.”