A few health insurers monopolise US market

Mergers between health insurance companies have created virtual monopolies that limit consumer choice, do not offer savings on premiums, and give doctors little or no bargaining power, a report from the American Medical Association claims. The past decade has seen more than 400 mergers among health insurance companies and managed care organisations, says the report, which analysed the insurance markets in nearly 300 metropolitan areas.

As of 2005, in 95% of these metropolitan areas, one insurer had at least a 30% market share. In 56% of areas, one insurer had more than half the …