Berkshire Hathaway buys additional 12 million shares of Occidental

July 7 (Reuters) - Warren Buffett's Berkshire Hathaway Inc bought another 12 million shares of oil producer Occidental Petroleum Corp, days after it purchased 9.9 million shares, according to a regulatory filing. (Reporting by Arunima Kumar in Bengaluru; Editing by Shailesh Kuber)