UnitedHealth (UNH.US) tumbled 8.08% to USD283.13 after-market as reported by The Wall Street Journal citing sources that the company is facing a criminal investigation into Medicare fraud. It is understood that the US Department of Justice has been investigating the company's Medicare Advantage business since last summer. UnitedHealth has declined to comment on the report.(Real-time Streaming US Stocks Quote; Except All OTC quotes are at least 15 minutes delayed.)Related NewsInflation Rate YoY for Apr in United States is 2.3%, lower than the previous value of 2.4%. The forecast was 2.4%.