Former UnitedHealth Group chief executive officer Stephen Hemsley to replace Andrew Witty. Here's what we know.

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 CEO Andrew Witty has stepped down unexpectedly and company veteran Stephen Hemsley is returning to the top role to steer the healthcare conglomerate through one of its most challenging periods.

Key Takeaways Shares of health insurance providers tumbled on a report UnitedHealth Group is being investigated by U.S. officials over possible fraud.The Wall Street Journal said the Department of Justice was looking into the company's Medicare Advantage business.

UnitedHealth Group is being investigated for possible Medicare fraud, according to The Wall Street Journal, sending shares of the healthcare company sliding in after-hours trading just one day after its CEO,