Medicare practices sent the stock diving Thursday to a five-year low. The Justice Department is looking into potential Medicare fraud by the health insurer, according to a report by the Wall Street Journal,

UnitedHealth Group has said it has not been notified by the Department of Justice of a reported criminal investigation. The Wall Street Journal reported on Wednesday that the firm is facing a DOJ investigation for possible Medicare fraud,

UnitedHealth Group, one of America’s largest health insurers, is facing a storm of challenges—from a criminal investigation to a leadership shake-up—that have rattled markets and erased billions in shareholder value.