The biggest insurer in the nation has exited the Obamacare exchanges in Arkansas and Georgia, as insurers struggle financially in the exchanges.

UnitedHealth will leave the two states and not sell plans in Arkansas and Georgia. The move comes as UnitedHealth has detailed more than $400 million in losses in the Obamacare exchanges and threatened to leave the exchanges altogether.

Other major insurers such as Cigna have said they are losing money but have remained committed to the exchanges. The reason is that they hope the markets will stabilize and the exchanges eventually will become profitable.

UnitedHealth did not immediately return a request for comment. The insurer has previously said that it may have to leave the entire Obamacare business due to mounting losses.

The Obama administration has made several moves aimed at appeasing insurers concerned over profitability in the exchanges. Among the moves is a decision to eliminate numerous special enrollment periods that allow people to sign up for Obamacare year-round.