Berkshire Hathawaythe investment firm of Warren Buffett, is still strengthening on the file of the oil group Occidental Petroleum, bringing its stake to more than 22% according to the latest statements to the SEC, the American market authority. Berkshire thus acquired approximately 5.8 million additional Occidental shares on Friday, Monday and Tuesday. It had been several months since the firm of the Oracle of Omaha had not changed its position in the round of the oil and gas group. Berkshire paid around $355 million for the acquisition of its additional securities in recent days. The firm’s previous declared purchases on the Occidental dossier date back to September. Participation at the end of December was 21.4%. In August, Berkshire had obtained approval from the US Federal Energy Regulatory Commission to buy up to 50% of Occidental’s common stock. Buffett’s firm now owns more than 200 million shares of the Houston oil group worth around $12 billion. Berkshire also owns $10 billion of Occidental preferred stock, as well as warrants to purchase an additional $5 billion of common stock.