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Aetna Inc.

Insurer Aetna lays out concerns about ACA exchange business

Aetna has joined other major health insurers in sounding a warning about the Affordable Care Act's public insurance exchanges.

The nation's third-largest insurer said Monday that it has been struggling with customers who sign up for coverage outside the ACA's annual enrollment window and then use a lot of care. This dumps claims on the insurer without providing enough premium revenue to counter those costs.

The ACA provides an annual enrollment window that gives people several weeks starting every fall in which they can buy coverage for the next year. The law established that window to prevent people from waiting until they become sick to buy insurance. But insurers say it...