Aetna, the U.S.'s third largest health insurance company, says it will cut its participation in the Affordable Care Act's marketplaces next year by two-thirds, after the Department of Justice moved to block its merger with another healthcare company. Aetna claimed it faces more than $300 million in losses this year as a result of the public exchanges. But in a letter sent to the Justice Department in July, Aetna CEO Mark Bertolini threatened that Aetna would reduce its participation in the exchange if the Justice Department blocked its merger with health insurance company Humana. Bertolini wrote: “If the DOJ sues to enjoin the transaction, we will immediately take action to reduce our 2017 exchange footprint.” Aetna reported a 38 percent increase in its overall profits last year, despite the loss it reported on the public exchanges. Last month, the Justice Department also sued to block a merger between healthcare giants Cigna and Anthem, which would be the largest heath insurance merger in U.S. history.