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. Chairman Stephen Hemsley will become CEO, effective immediately, the Minnesota company said.

The moves follows Brian Thompson's murder, sharp public criticism, and a major blow to the insurer's stock price.

Witty will act as a senior advisor to his successor, Stephen Hemsley, who served as UnitedHealth Group's CEO from 2006 to 2017.