Buffett sparks UnitedHealth's biggest stock surge in 17 years

Group 1 - Warren Buffett has taken a $1.6 billion stake in UnitedHealthcare Group, leading to a significant increase in its share price, which is on track for its best one-day percentage gain since 2008, despite being down over 50% in the past year [1][2] - Following Buffett's investment, there has been increased interest in healthcare ETFs, specifically the Vanguard Health Care Index Fund ETF and the Health Care Select Sector SPDR Fund [2][3] - Berkshire Hathaway, Buffett's investment firm, is known for investing in undervalued businesses with long-term potential [5] Group 2 - UnitedHealthcare Group is currently under investigation by the Department of Justice, which has added to its challenges, alongside the fallout from the murder of executive Brian Thompson [6] - The murder of Thompson has drawn significant attention to the healthcare insurance system in the U.S., with Luigi Mangione charged in connection with the crime [6]