Buffett sparks UnitedHealth's biggest weekly stock surge in 16 years
1. Warren Buffett's $1.6 billion stake boosts UnitedHealth shares significantly. 2. Shares saw the largest one-day rise since March 2020. 3. Despite gains, stock remains down over 50% year-over-year. 4. Department of Justice probes could affect investor sentiment. 5. Executive Brian Thompson's murder remains a troubling issue.