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.

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.

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

In February, the Journal reported a civil fraud investigation into UnitedHealth's Medicare practices. The company had then said that it was unaware of any new probe.

Hemsley, 72, had led the company for more than a decade until 2017 and is re-taking the reins following a series of setbacks.

UnitedHealth has faced several headwinds in the recent past, ranging from a cyberattack, which had greater than initially realized impacts, to the tragic killing of its CEO, which caused the company to suffer harsh public backlash over the company's and industry practices.

UnitedHealth's stock has plunged nearly 40% year-to-date as the company has battled a series of crises. Can the healthcare giant turn it around? Seeking Alpha analysts weigh in.

British boss of US healthcare giant UnitedHealth quits for ‘personal reasons’ - The move comes five months after one of the company’s top executives was killed after being shot as he walked to an investor conference in New York.