Most Americans get their health insurance through their employers, or via Medicare or Medicaid. But millions who lack those options use the insurance markets set up under the law.
It has turned out that so many marketplace customers need expensive medical care that some insurers are spending more on claims than they earn in premiums. And the federal government's strategies for protecting insurance companies from large losses have not been as effective as hoped.
Insurers, including a few big ones like Aetna and Humana, are withdrawing from the marketplaces in many states, saying they are losing too much money.
