He played a significant role in the company's growth, particularly after the acquisition of Peak Health Plan, where he served as president and chief operating officer.
When McGuire joined UnitedHealth Group, it was an unprofitable regional health maintenance organization with annual revenues around $400 million.
[2] When he left, UnitedHealth Group the company had more than $70 billion in annual revenues, more than 50,000 employees, and more than sixty million health plan members.
In 2006, the Securities and Exchange Commission began investigating the conduct of UnitedHealth's management and directors, including McGuire, as did the Internal Revenue Service and prosecutors in the United States Attorneys' office for the Southern District of New York.
McGuire was fined $7 million[7] and agreed to not serve as an officer or director of a public company for ten years.
[12] In October 2009, McGuire and his wife Nadine donated a rare butterfly collection valued at $41 MM to the University of Florida.