Aetna will exit 11 of the 15 state marketplaces where it currently offers coverage on the Affordable Care Act, citing the same “continued financial stress” as other large insurers that are scaling back exchange business in 2017.

“Following a thorough business review and in light of a second-quarter pretax loss of $200 million and total pretax losses of more than $430 million since January 2014 in our individual products, we have decided to reduce our individual public exchange presence in 2017, which will limit our financial exposure moving forward,” said Aetna CEO Mark Bertolini.

He cast blame on the risk pool in the ACA exchanges, saying individuals “in need of high-cost care” made up a greater share of Aetna's members in the second quarter of 2016.

“This population dynamic, coupled with the current inadequate risk adjustment mechanism, results in substantial upward pressure on premiums and creates significant sustainability concerns,” Bertolini said.

Aetna will still offer plans on exchanges in Delaware, Iowa, Nebraska and Virginia next year.

The departures are a reversal of what Bertolini had said in April, when he called the exchanges a “good investment” and raised its earnings forecast just days after UnitedHealth had announced its departure from all but a “handful” of states. In May, a company spokesman said it had “no plans at this point to withdraw from any” of the 15 states where it offered coverage in 2016.

The company’s tone appeared to change after the U.S. Department of Justice filed an antitrust lawsuit against the company’s proposed acquisition of Humana on July 21.

On Aug. 2, Aetna’s second quarter earnings report projected it would lose $300 million on its exchange business, leading Bertolini to announce any expansion plans would be halted and a “complete evaluation” of its future participation. The departure announcement followed on Aug. 15.

When asked by HealthExec if the change in exchange participation had anything to do with the DOJ lawsuit, Aetna spokesman T.J. Crawford said “this is a business decision based on higher than projected medical costs.”

“As a result of these losses, significant structural challenges facing the public exchanges, an uncertain policy outlook and so many other payers exiting the exchanges, we cannot responsibly maintain our current footprint,” Crawford said.

Aetna’s partner in the contested merger, Humana, also announced it would scale back its exchange participation after the lawsuit was filed, though it had first said in May, months before DOJ sued, that it would leave some states.  

Despite the departure of the three of the nation’s largest insurers, HealthCare.gov CEO Kevin Counihan remains optimistic about what the marketplaces will offer consumers next year.

“It’s no surprise that companies are adapting at different rates to a market where they compete for business on cost and quality, rather than by denying coverage to people with pre-existing conditions,” Counihan said.

Aetna’s exit could lead to a new challenge for the exchange: what to do when no insurers offer plans in a certain area.

That’s the risk in Pinal County, Arizona, where the Wall Street Journal reported no insurers have filed to offer coverage to exchange customers for 2017. Arizona Department of Insurance spokesman Stephen Briggs told WSJ regulators are speaking to other insurers about exchange participation, but cautioned the department doesn’t “have any legal leverage to compel anyone to offer a plan.”