Warren Buffett walks the floor and meets with Berkshire Hathaway shareholders ahead of their annual meeting in Omaha, Nebraska on May 3rd, 2024.David A. Grogen | CNBCThe mystery over Warren Buffett's surprisingly defensive stance deepened over the weekend.The 94-year-old CEO of Berkshire Hathaway sold more stocks in the latest quarter and grew a record cash pile even larger to $334 billion, but failed to explain in his highly anticipated annual letter why the investor known for his astute equity...