Battle of the market caps: Exxon beat Apple by $30B by Philip Elmer-DeWitt @FortuneMagazine January 2, 2012, 4:05 PM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons Exxon Mobil finished 2011 where it started: As the world’s most valuable company Source: Wolfram Alpha It was nip and tuck for more than three months, from that day in early August, when Apple AAPL first overtook Exxon Mobil XOM , to mid November, when Exxon finally pulled away. At one point in late September, Apple’s market cap (share price times number of outstanding shares) was nearly $36 billion more than Exxon’s. But though Apple’s shares ended the year having gained more than Exxon’s (25.1% to 15.5%), it was not enough to overtake Exxon’s initial lead. Exxon finished 2011 $30 billion ahead of Apple. The fact is, the world can live without iPhones and iPads. It still can’t get along without oil.