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.

The U.S. Department of Justice is carrying out a criminal investigation into UnitedHealth Group for possible Medicare fraud, the Wall Street Journal reported on Wednesday.

An analyst reluctantly downgraded UnitedHealth’s stock, as the price plunge and a suspended full-year outlook was just too much to hold a bullish stance.