At the end of last year, Warren Buffett stepped down as CEO of Berkshire Hathaway (NYSE: BRKA)(NYSE: BRKB) after leading the charge for 60 years. Their strategies differ, but one thing that remains consistent is Berkshire's recent interest in Alphabet (NASDAQ: GOOG) (NASDAQ: GOOGL). Berkshire began investing in Alphabet last year when Buffett was still CEO and has continued to increase its stake ever since. Buffett has said that he regrets not investing in Alphabet (then Google) earlier, but it's clear Abel isn't repeating that mistake. Berkshire recently invested $10 billion into Alphabet, one of its biggest deals in years.