Group 1 - Berkshire Hathaway has re-entered the healthcare insurance sector by purchasing 5.04 million shares of UnitedHealth Group, valued at approximately $1.57 billion as of June 30, marking its first investment in this sector since exiting in 2010 [1] - Following the news, UnitedHealth's stock price surged over 10% in after-hours trading, despite the stock having dropped nearly 50% year-to-date due to rising medical costs and other challenges [1] - Berkshire also sold 20 million shares of Apple, reducing its holdings to 280 million shares, while Apple remains the largest single stock in Berkshire's portfolio [1] Group 2 - Berkshire has established new positions in residential builder DR Horton and significantly increased its stake in Lennar, along with new investments in Allegion, Lamar Advertising, and Nucor, all of which saw varying degrees of stock price increases in after-hours trading [2] - The company sold approximately $3 billion more in stocks than it bought during the April to June period, marking the 11th consecutive quarter of net selling in U.S. equities, with cash and equivalents totaling $344.1 billion as of June 30 [2] - It remains unclear who is leading these transactions, whether it is Warren Buffett, investment managers Todd Combs and Ted Weschler, or successor candidate Greg Abel, but the market views Berkshire's purchases as endorsements of the respective companies [2]