Richard Burke + Paul Ellwood found Charter Med Inc 1974 in Minnesota; renamed United HealthCare Corporation 1977. Pioneers HMO 'managed care' concept — physician networks + capitation pricing reshape US healthcare delivery. Burke's vision: prepaid medicine inspired by Henry Kaiser's WWII shipyard plans.

Renamed UnitedHealthcare 1985 + IPO Oct 1984 at $7/share on Nasdaq; Bill McGuire joins 1988, becomes CEO 1991. Under McGuire UNH transforms from regional HMO into national managed care leader via UnitedHealthcare brand consolidation. Stock 1000x's by 2005 making McGuire one of the highest-paid CEOs in US history.

UnitedHealth options backdating scandal Oct 2006 — CEO Bill McGuire forced to resign over $1.6B in backdated stock option grants. UNH restates earnings; McGuire pays $620M penalty + returns $618M in options. Stephen Hemsley becomes CEO Dec 2006 — same Hemsley who returns as CEO May 2025 after Andrew Witty exit.

UnitedHealth launches Optum brand 2011 consolidating OptumHealth (services) + OptumInsight (data/analytics) + OptumRx (PBM). Optum becomes UNH's primary growth engine; by 2024 Optum delivers 50%+ of UNH profit. Stephen Hemsley CEO 2006-2017 + David Wichmann 2017-2021 + Andrew Witty 2021-2025.

UnitedHealth acquires Catamaran (PBM) Mar 2015 for $12.8B — adds OptumRx; combined OptumRx becomes #3 US PBM. Optum (UNH's services arm) grows from concept (2011) into $200B+ revenue business by 2024 — accounts for 50%+ of UNH profit by 2020s.

Andrew Witty becomes UnitedHealth Group CEO Feb 2021 — succeeds David Wichmann (CEO 2017-2021). Witty (former GlaxoSmithKline CEO) leads UNH through Change Healthcare ransomware crisis (Feb 2024) + Brian Thompson killing (Dec 2024) + Q1 2025 guidance pull. Replaced by Stephen Hemsley May 2025.

Change Healthcare cyberattack disclosed Feb 21 2024 — UNH discloses ALPHV/BlackCat ransomware on largest US clearinghouse; 14-day outage paralyzes claims/prescriptions nationally. CEO Andrew Witty testifies before Congress May 1 2024. Total impact $2.2B-2.45B 2024. Triggers HHS cybersecurity rulemaking + class action lawsuits.

UnitedHealthcare CEO Brian Thompson killed Dec 4 2024 outside NYC Hilton on way to investor day. Shooter Luigi Mangione arrested Dec 9 at Pennsylvania McDonald's; bullet casings inscribed 'deny, defend, depose' targeting insurance industry. UNH stock falls 9% in 5 days. Triggers national reckoning over US health insurance denial rates + prior authorization practices.

UnitedHealth Q1 2025 (Apr 17) misses revenue by $5B + pulls full-year EPS guidance entirely — first guidance pull in 20+ years. Cites MA medical-cost trends + Optum disability. Stock falls 22% in single day from $452 to $354. CEO Andrew Witty replaced May 13 2025 by Stephen Hemsley (board chair, prior CEO 2006-2017) — return-of-the-king moment.

UnitedHealth Optum DOJ criminal probe disclosed May 14 2025 — investigation into Medicare Advantage upcoding practices; UNH stock falls another 18% to $280 (trough). Multi-year crisis: Change ransomware (Feb 2024) → Thompson killing (Dec 2024) → Q1 miss + Witty exit (Apr-May 2025) → DOJ disclosure (May 2025). Stock recovers to $340 by Q1 2026.