(Reuters) -UnitedHealth Group CEO Stephen Hemsley will get an annual base salary of $1 million and a one-time $60 million equity award as he returns to the top role at a tough time for the healthcare conglomerate.

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

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

We don't need to dwell on the lack of detail behind Andrew Witty stepping down as CEO of UnitedHealth ( UNH) for "personal reasons." There are plenty of public reasons to change course at a business that has become a political lightning rod and Wall Street letdown.

Shares of UnitedHealth Group plunged more than 18% following a report that the Department of Justice is carrying out a criminal investigation into the health-care giant over possible Medicare fraud. The DOJ is reportedly focusing on the company's Medicare Advantage business practices,

UnitedHealth faces valuation reset amid CEO change, regulatory probes, and cost overruns. Click here for a full analysis of UNH stock.

UnitedHealthcare stock plunged again on Thursday after a new report in the WSJ said the company is facing a Medicare fraud probe.

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

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.