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, the largest health insurer in the country, is turning back the clock in a moment of crisis. On Tuesday, the company announced that chairman Stephen Hemsley is returning as CEO, stepping back into the role he left in 2017.

Former CEO and current chairman Stephen Hemsley is stepping back into the top job following the abrupt resignation of Andrew Witty, UnitedHealth said.

Even UnitedHealth will struggle to overcome parasitic medical costs that Warren Buffett once called a tapeworm eating away at U.S. economic competitiveness. The $300 billion healthcare conglomerate reinstalled Chairman Stephen Hemsley as CEO and yanked its financial guidance.

Robyn Denholm has earned five times as much as UnitedHealth Group's Stephen Hemsley, the next non-executive chair most prone to liquidating stock.

UnitedHealth Group Inc UNH announced Tuesday morning that its CEO, Andrew Witty, will resign for personal reasons.. Stephen Hemsley, who previously held the CEO title from 2006 to 2017, will succeed him. Hemsley will also remain chairman of UnitedHealth's board of directors, and Witty will become senior adviser to the CEO.

UnitedHealth Group Chairman Stephen Hemsley is returning to helm the health care conglomerate once again. He will replace Andrew Witty effective immediately.