UnitedHealth Group, which is the second-largest health insurer in Nebraska, announced earlier this year it would stop selling such policies in the state next year.

Those defections leave only two insurers, Aetna and Medica, serving people seeking individual policies on the exchange.

Blue Cross's move affects only the 20,000 or so of its customers who have individual policies bought on the federal marketplace exchange. The insurer will continue to offer small-group plans on the exchange as well as off-exchange individual plans that were grandfathered in before the law took effect in 2014.

And Blue Cross officials did leave the door open to possibly returning to the exchange if some fixes to the ACA are made.

Lew Trowbridge, president of Blue Cross and Blue Shield, said the federal government has to close some of the loopholes that allow people to enroll during so-called special enrollment periods. Trowbridge said too many people are gaming the system, getting coverage when they are sick or injured and then dropping it after receiving treatment.

Another issue that needs to be fixed are the risk pools. There are too many old and sick people getting coverage and not enough young and healthy ones.