So much for choice. In many parts of the country, Obamacare customers will be down to one insurer when they go to sign up for coverage next year on the public exchanges.

A central tenet of the federal health law was to offer a range of affordable health plans through competition among private insurers. But a wave of insurer failures and the recent decision by several of the largest companies, including Aetna, to exit markets are leaving large portions of the country with functional monopolies for next year.

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