UnitedHealth Group stock fell early Thursday following a report that the Justice Department is investigating the company for possible criminal Medicare fraud.The news comes only days after the struggling health insurer announced the departure of its CEO Andrew Witty due to personal reasons and suspended its full-year guidance citing high medical costs in its insurance division.

UnitedHealth Group CEO Stephen Hemsley, who replaced Andrew Witty, said he has the right strategy in place “for the era ahead.”