Updated

Health insurer Humana is leaving the Affordable Care Act's public insurance exchanges for next year as it regroups after ending its proposed combination with rival insurer Aetna.

Humana Inc. covers about 150,000 people on exchanges in 11 states.

The insurer said Tuesday it had taken several actions to improve that business, but it was still seeing signs of unbalanced risk in that customer population. Health insurers have struggled to attract enough healthy people to their risk pools to balance the claims they incur from people with expensive medical conditions.

Humana and Aetna said earlier Tuesday that they were calling off Aetna's roughly $34 billion acquisition of Humana. That deal already had been rejected by a federal judge who was worried about its impact on competition.