Health Care Service Corp. improved its net loss in 2015, but the Blue Cross and Blue Shield conglomerate continues to hemorrhage money in the Affordable Care Act’s nascent marketplaces.

HCSC, which owns the Blue Cross and Blue Shield affiliates in Illinois, Montana, New Mexico, Oklahoma and Texas, lost $1.5 billion on its individual ACA-compliant plans in 2015, according to financial filings. After factoring in a premium deficiency reserve, an accounting measure that predicts future losses, the insurer lost $866 million last year on its ACA plans, said Ken Avner, HCSC’s chief financial officer.