UnitedHealth Group shares plunge 18% on reported DOJ probe into possible Medicare fraud
1. UnitedHealth shares fell 18% due to DOJ's criminal investigation news. 2. Investigation focuses on Medicare Advantage business practices amid unclear allegations. 3. The company's CEO transitions back to former CEO Stephen Hemsley. 4. UNH’s market cap has decreased by $300 billion in one month. 5. The company faces potential removal from the Dow Jones Industrial Average.