UnitedHealth Group’s stock fell Thursday after the company confirmed government criminal and civil investigations into its Medicare practices but stressed that it doesn’t expect to be charged with any wrongdoing.

UnitedHealth Group confirmed that its Medicare Advantage program is under investigation by the U.S. Department of Justice.

The disclosure sent UNH shares tumbling 4.7%, reflecting investor unease with the ongoing troubles with the healthcare stock. This admission adds to a string of challenges that have battered the company, with its stock now trading 56% below its 52-week high.