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.

UnitedHealth Group stock fell sharply Friday following a report that said the Justice Department had launched a civil fraud investigation into the company’s Medicare billing practices. The stock fell 12% to $444.

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

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.

It extends a tumultuous period for UnitedHealth marked by the killing of a top executive, a costly cyberattack against its subsidiary and high medical costs.

UnitedHealth (UNH) stock was down Friday on a report from The Wall Street Journal that the health insurance company faces a Department of

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