Health insurers will lose about $2.5 billion because patients covered through President Barack Obama’s health law last year were sicker than expected, according to government figures released late Thursday.

The Department of Health and Human Services released updated numbers for a program that helps stabilize premiums in the health care law’s insurance markets, which offer taxpayer-subsidized private plans. Under that program, insurers whose medical claims costs were lower than expected pay in money to help insurers whose costs were higher.