Stephen Hemsley will also get additional personal security benefits following the December murder of UnitedHealth’s top insurance executive.

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.

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 faces a U.S. Department of Justice criminal investigation for potential Medicare fraud, as reported by the Wall Street Journal. This follows CEO Andrew Witty's unexpected departure and a suspended financial forecast due to rising medical costs,

UnitedHealth Group surprises investors with what its CEO said was an "unusual and unacceptable" quarterly earnings miss, and lowers its outlook for the full year due to higher-than-expected medical costs, sparking a more than 20% selloff in shares that reverberated across the sector.