UnitedHealth Under Investigation by Justice Department for Medicare Billing Practices

The U.S. Justice Department has commenced an investigation into UnitedHealth's Medicare billing practices, according to the Wall Street Journal.

The investigation centers around potential fraud in the insurer's recording of diagnoses that justify increased payments to its Medicare Advantage plans. The scrutiny extends to physician groups owned by the insurance giant.

Shares of UnitedHealth declined approximately 7% to $466.88 in premarket trading following the news.

Both the Justice Department and UnitedHealth have yet to provide a response to Reuters' request for comment.