The CEO of UnitedHealth Group defended the company's role in the U.S. health care system days after a report said the company made huge profits by significantly marking up the cost of lifesaving drugs.

After reporting weaker than expected results for the company’s insurance division, UnitedHealth CEO’s said his company was not to blame for the high cost of healthcare in the U.S.

UnitedHealth Group shares have lost more than $63 billion in value since the murder of UnitedHealth CEO Brian Thompson in early December.

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.”

UnitedHealth CEO Andrew Witty said on Thursday that healthcare in the U.S. needs to be "less confusing, less complex and less costly" during the company's first earnings call since the murder of Brian Thompson,

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.