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

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

UnitedHealth Group Chairman Stephen Hemsley is returning to helm the health care conglomerate once again. He will replace Andrew Witty 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. Hemsley was UnitedHealth Group CEO from 2006 to 2017. He will remain chairman of the company’s board. Witty will serve as a senior adviser to Hemsley.

UnitedHealth Group CEO Andrew Witty abruptly stepped down from the health insurance and care conglomerate on Tuesday, citing personal reasons, capping the end of a tumultuous four-year tenure that included the killing of the company’s top insurance executive .

Andrew Witty is stepping down as CEO of health care giant UnitedHealth Group in a surprise transition that follows a period of unprecedented turbulence, including the public killing of a company executive and financial woes that in recent weeks have only intensified.

As CEO for more than a decade, Stephen Hemsley built up UnitedHealth Group, now a $400 billion healthcare behemoth. With his return to the top job, the company will learn whether his playbook still works.