A shopping cart at a Wal-Mart store in Los Angeles.
Robyn Beck /AFP/Getty Images
May 6, 2013 Facebook, which went public in May of 2012, made the list for the first time. Its CEO, Mark Zuckerberg, 28, is the youngest on the list.
At an Exxon Mobil gas station in Chicago; July 29, 2010.
John Gress/Getty Images
May 7, 2012 With 2011 revenues of $452.9 billion, the oil and energy giant edged out Wal-Mart Stores, which brought in $447 billion, Fortune magazine says.
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