Warren Buffett’s successor released his first letter to Berkshire Hathaway shareholders on Saturday as the company took a $4.5 billion write-down on the value of its Kraft Heinz and Occidental Petroleum stakes. Greg Abel took over as CEO in January. 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 because it has worked so well over the past six decades. And Buffett remains chairman and the largest shareholder. But Abel is now writing the annual letters that were always known as one of the most-read business reports. No one is expecting him to match Buffett's wit.