The justice department is examining how the insurer’s methods of recording patient diagnoses could result in excess payments to UnitedHealth’s Medicare Advantage plans, a privately run offshoot of the government-backed health insurance programme, said people familiar with the matter.

UnitedHealth Group stock tumbled following a report that said the Justice Department had launched a civil fraud investigation into the company’s Medicare billing practices.The DOJ probe aims to examine the healthcare company’s practices for documenting diagnoses that trigger extra payments to its Medicare Advantage plans,