Occidental Petroleum is one of Berkshire Hathaway's top holdings for a reason.Occidental Petroleum (OXY 3.16%) is a leading diversified energy company. It has global oil and gas operations, marketing and midstream operations, a chemicals business, and a lower-carbon energy segment. The company's high-quality operations and management team have made it a top holding of Warren Buffett's Berkshire Hathaway. Here's a look at whether the oil stock has beaten the market over the past five years and if it could do ...