UnitedHealth Group is currently under investigation by the U.S. Department of Justice (DoJ) for potential Medicare fraud, according to multiple reports. The news comes amid a tumultuous period for the company, which saw its stock plummet over 8% in after-hours trading following the revelation. Despite the serious allegations, UnitedHealth has stated that they have not been officially notified by the DoJ about the supposed criminal investigation. The situation adds to the pressures the company is currently facing, including executive changes and market challenges.