Humana says the company as a whole is doing well, but that its individual health operations are doing much worse than it had expected.
The Louisville, Kentucky-based health insurance giant says it will sell individual health coverage in no more than 156 counties in 11 states in 2017, down from 1,351 counties in 19 states this year.
That will reduce the number of counties in which it sells individual exchange plans by at least about 88 percent.
The company is pulling out of the off-exchange individual health insurance market in all states.
The company started the year with about 1.1 million individual health enrollees. The company provides or administers coverage for about 14 million people.
The company predicts those changes will reduce its revenue from individual health coverage that comply fully with the Affordable Care Act to about $750 million to $1 billion next year, from about $3.4 billion this year.
The company also is recording two charges related to the individual health business: a $208 million increase in its individual health premium deficiency reserve for 2016, and a $52 million charge related to the ACA risk management programs and claims from earlier quarters.