UnitedHealth Group shares plunge 18% on reported DOJ probe into possible Medicare fraud

Core Points - UnitedHealth Group's shares fell over 18% following reports of a criminal investigation by the Justice Department regarding potential Medicare fraud [1] - The investigation is focused on the company's Medicare Advantage business practices, with previous civil investigations into inflated diagnoses for extra payments [2] - The company has experienced a significant decline in market cap, losing over $300 billion in one month, and is facing risks of being removed from the Dow Jones Industrial Average [4] Company Developments - UnitedHealth Group stated that it has not been notified about the reported investigation and defended the integrity of its Medicare Advantage program [2] - The company recently saw the unexpected departure of CEO Andrew Witty, with Stephen Hemsley returning as the new CEO [3] - The company has faced multiple challenges this year, including a historic cyberattack and higher-than-expected medical costs [4]