UnitedHealth Group is a multinational healthcare giant based in Eden Prairie, Minnesota, operating through its insurance arm UnitedHealthcare and its services arm Optum. It is the world's fourth-largest company by revenue and the largest healthcare company by revenue, with a market capitalization exceeding $400 billion and over 50 million insured Americans. Founded in 1974 by Richard Taylor Burke as Charter Med, it went public in 1984, adopted its current name in 1998, and grew through major acquisitions like Oxford Health Plans and PacifiCare. The company has faced significant legal scrutiny, including a 2006 stock option backdating scandal that forced CEO William W. McGuire to resign, replaced by Stephen Hemsley. It has also been investigated and fined for Medicare over-billing, unfair claims practices, and denying mental health treatments.