UnitedHealth Group’s stock plummets after DOJ investigation report - UnitedHealth Group have had a tumultuous past year, including the fatal shooting of UnitedHealthcare CEO Brian Thompson

UnitedHealth Group (UNH) stock crashed on Friday morning in light of a new United States (US) Department of Justice (DOJ) probe into possible overcharging of the federal government entity for retiree health services. UNH stock plunged as much as 12.7% at the open, but shares are now down about 9% closer to lunchtime near $457.

The health insurance giant has called a new report from WSJ “misinformation,” but investors may not be so sure. Shares were down about 9% early Friday. UnitedHealth Group, America’s largest insurer, is facing yet another crisis.

UnitedHealth, still reeling from the murder of one of its top executives, is reportedly facing a Department of Justice investigation.

The Justice Department is probing diagnoses and practices that triggered extra payments to UnitedHealth’s Medicare Advantage plans, people familiar with the matter say.

The U.S. Justice Department has launched an investigation into UnitedHealth's Medicare billing practices in recent months, the Wall Street Journal reported on Friday, citing people familiar with the matter.

Any suggestion that our practices are fraudulent is outrageous and false," the insurer said.