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.

Key Takeaways Shares of UnitedHealth Group sank Friday following a report that the U.S. Department of Justice is investigating the company's diagnosing practices.The Wall Street Journal reported that the DOJ is probing whether the company tends to over-diagnose conditions that can earn larger Medicare Advantage payouts.

UnitedHealth Group (UNH) is under fire over its Medicare billing practices. The Wall Street Journal reported Friday that the U.S. Department of Justice (DOJ) has launched a civil fraud investigation into how the company records diagnoses that lead to extra payments for its Medicare Advantage plans.

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.

UnitedHealth Group called The Wall Street Journal's report "misinformation" and said it was unaware of reported investigaiton.

UnitedHealth Group (UNH) stock drops 7% as the company becomes the subject of a new investigation from the U.S. Department of Justice. Read more here.

UnitedHealth Group stock is sinking Friday on reports the Justice Department is investigating the health insurer. Here's what to know.

UnitedHealth Group shares tumbled Friday on a report that the U.S. Department of Justice has started an investigation into the health care giant’s Medicare billing practices