The ink on Exxon Mobil's balance sheet comes in one grade: Premium. The energy giant fell just short of setting a company -- and world -- record for profits this year. The last world record was set by -- you guessed it -- Exxon Mobil, back in 2008. The abundance of cheaper domestic energy both hurt and helped the company in 2012. A greater supply of U.S. crude and natural gas drove production revenues down. But it was Exxon's refineries that saved the day. With supplies close at hand, making fuel was a lot cheaper, which helped boost profits. -- Tom Ziegler
Wal-Mart retook the top spot, Berkshire Hathaway made the top five, and Apple grew enormously.