Stephen Hemsley hasn’t been CEO at UnitedHealth Group in nearly a decade yet he’s never really left. Hemsley, 72, has remained chairman and a major shareholder in the health care behemoth — and now is back in the CEO suite and is expected to reinstate his brand of operational and financial discipline that turbocharged the company’s growth.

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

May 13 (UPI) -- UnitedHealth Group announced Tuesday CEO Andrew Witty will step down, citing "personal reasons." Witty will leave the role of CEO and be replaced by Stephen J. Hemsley, effective immediately.

UnitedHealth CEO Andrew Witty is stepping down for personal reasons and the nation's largest health insurer suspended its full-year financial outlook due to higher-than-expected medical costs. Chairman Stephen Hemsley will become CEO, effective immediately, the Minnesota company said.

UnitedHealth Group announced that CEO Andrew Witty is stepping down due to 'personal reasons,' Stephen Hemsley will replace him.

UnitedHealth Group's stock has plunged nearly 50% due to the CEO resignation, withdrawal of guidance, and ongoing legal issues, creating a potential buying opportunity. The stock is deeply oversold with an RSI of 15, trading below both the 200-day and 50-day moving averages, indicating capitulation.

UnitedHealth Group Chief Executive Officer Andrew Witty stepped down, effective immediately, "for personal reasons", the company said Tuesday. “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 statement shared by UHG.

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