Sales at Wal-Mart exceeded those of oil giant Exxon, leaving the US discount behemoth to top Fortune magazine's list of the 500 largest companies in the world; the first service company to ever reach those heights. Wal-Mart's revenues reached US$219.8bn last year, higher than the US$191.6bn posted by Exxon Mobil, which in turn overtook pole position from General Motors in 2000.