Key Takeaways UnitedHealth Group is reportedly under an antitrust investigation by the U.S. Department of Justice. Officials are apparently looking into the relationship between the company's UnitedHealthcare and Optum units. Shares of UnitedHealth Group tumbled following the news. UnitedHealth Group (UNH) shares were down nearly 5% Wednesday afternoon following a report that the giant health insurance provider is under a federal investigation for potential antitrust violations. The Wall Street Journal repo ...