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.

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 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.

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.