The stock is having its worst day in five years, even as the company denied any new Justice Department investigation and a Mizuho analyst recommended buying.

Key Takeaways U.S. equities dropped at midday following the latest data on consumer sentiment and a report that UnitedHealth Group is under a federal probe. UnitedHealth Group is said to be facing a Department of Justice probe of its Medicare billing practices.

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

While Luigi Mangione today stands trial for the killing of UnitedHealthcare CEO Brian Thompson, the U.S. Justice Department is launching a civil fraud investigation into the conglomerate’s Medicare billing practices.