Warren Buffett’s Berkshire Hathaway has bought another 4.3 million shares in Occidental Petroleum, bringing its total stake in the company to 19.2 percent, Reuters has reported, citing an SEC filing by Buffett’s investment vehicle. The stock purchase is the latest in a series that has seen Berkshire Hathaway increase its interest in Oxy from less than 14 percent to close to 20 percent. This has prompted talk that the investment firm might be planning to take over the oil major. Three years ago, Berkshire Hathaway funded Oxy’s…