Shell jumps ahead of Wal-Mart, ExxonMobil as world's largest company

There's a new number one in town, and it's a bit of a surprise. According to the Fortune Global 500 ranking of the world's largest corporations, Royal Dutch Shell (RDS) leapfrogged over Wal-Mart Stores (WMT) and ExxonMobil (XOM) to take the top spot. Royal Dutch Shell pulled in $15 billion more in sales than ExxonMobil last year, with ExxonMobil coming in second, and Wal-Mart falling all the way to third in terms of revenue.

Royal Dutch Shell is Europe's largest oil producer and aims to stay that way (and to stay on the top of Fortune's rankings) with its $18 billion investment in a plant in Qatar that will turn natural gas into cleaner-burning diesel fuel. This facility is expected to be up and running by 2010 and the company believes it will produce enough fuel to fill more than 160,000 cars per day. ExxonMobil remained in the second spot, thanks to $443 billion in revenue and $45 billion in earnings. Wal-Mart slipped despite a solid year as the "hottest stock in the Dow Jones Industrial Average in 2008."