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 disclosed the stake in a Friday night filing with the U.S. Securities and Exchange Commission. Occidental’s share price, which jumped 45 percent last week, rose as much as 4.7 percent on Monday before retreating. The shares were down 4.8 percent at $53.45 in early afternoon trading. Occidental traded below $9 as recently as October 2020. Oil prices have surged higher following Russia’s invasion of Ukraine last month, prompting fears of supply shortages. Berkshire also has warrants to buy another 83.9 million Occidental shares at $59.62 each, or $5 billion. It obtained these in 2019, when …