Headquarters: Irving, Texas
Revenue: $449.9 billion
Profit: $44.9 billion
2012 rank: 1
ExxonMobil (another descendant of Standard Oil) lost the top spot in the Fortune ranking this year, but not for any lack of success. Its $44.8 billion profit in 2012 was its highest ever, and the second-highest in US history. In terms of stock market value, it’s the largest company in the world, just edging out Apple. It's also the world's largest oil refiner.