Occidental Petroleum stock is down Wednesday as Berkshire Hathaway ramps up its stake in the oil company.<br /><br />The Warren Buffett-backed conglomerate owns 24.9% of Occidental Petroleum after buying about $275 million of stock in the energy company recently, Barron's reports.<br /><br />The firm procured 4.66 million shares of Occidental Petroleum on Thursday, Friday, and Tuesday in the open market, bringing its total ownership to 222 million shares worth $13 billion.
