Warren Buffett's successor released his first letter to Berkshire Hathaway shareholders on Saturday as the company took a USD 4.5 billion write-down on the value of its Kraft Heinz and Occidental Petroleum stakes. Greg Abel took over as CEO in January, so this is his chance to set the tone for his leadership. Investors are watching closely for any changes he might make, but Abel and Buffett have said there won't be significant changes in the way Berkshire operates. The letter opens with a tribute to Buffett and a promise to maintain Berkshire culture and continue operating the same way that has worked so well for six decades. And Buffett remains chairman and the largest shareholder, so he's still helping guide the Omaha, Nebraska-based conglomerate he built. But Abel is now writing the annual letters that were always known as one of the most-read business reports out there because so many investors admired and followed Buffett because of his remarkable track record, homespun wit and