CMS also said that it expects the risk pool to keep growing and to improve as a result of several actions planned by the agency, including strengthening the outreach it makes to people, particularly young adults, which will include reminding them of the tax penalty for failing to have insurance.
Levitt said that while the data suggest that the risk pool improved in 2015, the second year of Obamacare sales, "there's no systematic data yet on what 2016 looks like."
"Individual insurers can see how their own risk pools and finances are shaping up, but no one insurer has the full picture," he said.
Robert Laszewski, president of Health Policy and Strategy Associates, said, "What is most significant about Aetna's reasoning for dramatically cutting back on its participation in the ACA exchanges is that it is saying the claims experience is getting worse not better."
"People had hoped the risk pool would have stabilized midway through the third year," Laszewski said. But "other carriers [insurers] I talk to are finding the same continued deterioration in the risk pool."
"What I find most disconcerting is that the local Blue Cross plans are in a real bind here," he added. "One plan after another is reporting unsustainable underwriting results in the ACA exchanges but, given their long-standing commitment to their states, it isn't so simple for them to walk away as the big for-profits like United, Humana and now Aetna are doing."
"I don't think you can underestimate just how critical the instability of the ACA risk pool is," Laszewski said.