Last November, when UnitedHealth Group said it expected to post big losses on its Obamacare policies in 2016, rivals such as Anthem and Aetna signaled their Affordable Care Act businesses were doing fine. The Obama administration used that as evidence to refute claims that systemic problems were brewing in its landmark insurance program.

Now, there’s no denying it. The four biggest U.S. health insurers admit they’re each losing hundreds of millions of dollars on their Obamacare plans. Rather than expand coverage, many are pulling out of the exchanges that were set up by the ACA so people can shop for insurance plans, often with the help of government subsidies.

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