Four Dallas-Fort Worth companies are among the 2013 Fortune Global 500 list, led by Irving-based Exxon Mobil Corp. (NYSE: XOM) at No. 3. Exxon, which has 2012 revenue of $449.9 billion in 2012, was joined by Dallas-based AT&T Inc. (NYSE: T) at No. 34 with $127.4 billion in 2012 revenue; Irving-based Fluor Corp. (NYSE: FLR) at No. 422 with $27.6 billion; and Fort Worth-based AMR Corp. (OTC: AAMRQ) at No. 469 with $24.9 billion in 2012 revenue. Royal Dutch Shell led the list with $481.7 billion in 2012 revenue, with Wal-Mart Stores at No. 2 with $469.2 billion in revenue. AMR, of course, is in the midst of a merger with US Airways Group (NYSE: LCC) to create the world’s largest airline company, likely moving the new American Airlines up the list next year. You can see the full list of the Fortune Global 500 here.