UnitedHealth reported fourth-quarter results on Thursday that reflected persistent challenges for the health insurance sector.

The UnitedHealth Group leader whose murder in December unleashed a torrent of public frustration and dissatisfaction with the U.S. health care system was pushing for some of the very improvements that critics have been seeking.

In his first public comments since one of his executives was shot to death, UnitedHealth Group CEO Andrew Witty said the healthcare system “needs to function better.”

In its first results since its insurance unit CEO was fatally shot in New York City, UnitedHealth Group reported Thursday weaker-than-expected fourth-quarter revenue, prompting its shares to fall in early morning trading despite quarterly profit beating projections.

The CEO of UnitedHealth Group has defended its role in America's health system as the company posted its first earnings results since the murder of one of its top executives. Sir Andrew Witty spoke to analysts as the firm reported mixed results,

UnitedHealth Group held its first earnings call since the shooting of its insurance executive last month. UnitedHealthcare CEO Brian Thompson was killed outside of an investor day