OMAHA, Neb.—Warren Buffett’s company has bought up more than $11 billion worth of Occidental Petroleum stock this year, giving Berkshire Hathaway control of more than 20 percent of the oil producer. Occidental’s stock rose more than 3.5 percent on Tuesday to $62.18 after Buffett revealed his latest purchases of nearly 6.7 million Occidental shares worth…

Warren Buffett’s Berkshire Hathaway Inc has bought another 5.9 million shares of Occidental Petroleum Corp, boosting its stake in the oil company to about 15.2 percent. The purchases were made on Monday and Tuesday and cost about $336 million, Berkshire said in a regulatory filing on Wednesday night. Following the purchases, Berkshire owned 142.3 million…

Warren Buffett’s Berkshire Hathaway Inc. revealed a more than $5 billion stake in Occidental Petroleum Corp., as oil prices soared to their highest level in about a decade. Berkshire said it owns 91.2 million Occidental shares, or nearly 10 percent of those outstanding, including 61.4 million bought from March 2 to March 4. Buffett’s company…