Warren Buffett's Berkshire Hathaway has made significant investments in three key stocks: Amazon, Visa, and Chubb, which are poised for long-term growth. Amazon, holding 0.70% of the portfolio, has seen its value more than double since its initial purchase in 2019, driven by robust revenue growth and a strong cloud infrastructure. Visa, accounting for 1% of the portfolio, has also thrived, achieving a six-bagger gain since 2011, with consistent revenue and earnings growth through economic fluctuations.