Group 1 - Berkshire Hathaway is secretly buying a "mystery stock" and has applied for confidentiality to avoid stock price fluctuations due to large-scale operations [1] - The total stock investment of Berkshire has reached approximately $275 billion, and any new investment typically requires a scale of several billion dollars [1] - The confidentiality application may also involve investment partners Todd Combs or Ted Weschler, especially with Warren Buffett set to step down as CEO by the end of the year [1] Group 2 - In late 2023 to early 2024, Berkshire applied for confidentiality while quietly purchasing shares of Swiss insurance company Chubb, with current holdings amounting to about $8 billion [2] - Previous "mystery stocks" included Chevron and Verizon, where Berkshire also opted for confidentiality during the acquisition process [2] Group 3 - The Q1 financial report did not reveal specific details about the current "mystery stock," but indicated an increase of approximately $2 billion in the "commercial, industrial, and other" stock holdings [3] - The consumer goods sector saw an increase of $1.1 billion in holdings [3] Group 4 - Recent activities include Berkshire doubling its investment in Constellation Brands, increasing holdings in Domino's Pizza, Pool Corp., and Heico [4]