Shares of UnitedHealth Group slumped 6% in premarket trading Thursday on a report that the U.S. Department of Justice is investigating the embattled health insurance provider for possible criminal Medicare fraud.

Stephen Hemsley ran UnitedHealth Group for more than a decade. It's a different company after four years with Andrew Witty in charge.

UnitedHealth Group's stock has collapsed nearly 50% in 2025 after a leadership shake-up, surging medical costs, and a DOJ criminal probe into Medicare fraud.

"Leading the people of UnitedHealth Group has been a tremendous honor as they work every day to improve the health system and they will continue to inspire me," Witty said in a st

Andrew Witty has resigned as chief executive of US health conglomerate UnitedHealth Group, as the company pulled its financial forecasts for 2025, adding to a sense of crisis after a turbulent period.

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