UnitedHealth is almost as oversold as during the Great Financial Crisis, with its monthly RSI sitting at 33. Find out why UNH stock is a Buy.

The reported probe adds to a string of recent setbacks that have erased more than half, or over $300 billion, from its market value since November.

Shares of UnitedHealth Group tumbled 16% in intraday trading Thursday, leading S&P 500 decliners, on a report that the U.S. Department of Justice is investigating the embattled health insurance provider for possible criminal Medicare fraud.