Department of Justice is investigating UnitedHealth, company says it is cooperating

UnitedHealth Group said Thursday that the medical-insurance company is cooperating with the Justice Department in the agency's requests for criminal and civil matters. 

The company "has a long record of responsible conduct and effective compliance,” the company said in a Securities and Exchange Commission filing, according to the Associated Press.

UnitedHealth Group's stock price slipped another 2%, or $5.12, to $287.39 on Thursday morning.

According to The Wall Street Journal earlier this year, federal officials had launched a civil fraud investigation into how the company records diagnoses that lead to extra payments for its Medicare Advantage plans, which are privately-run versions of the government's Medicare coverage program.

UnitedHealth Group said it contacted the DOJ “after reviewing media reports about investigations into certain aspects of the company’s participation in the Medicare program.”