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St. Louis, MO (KSDK) -- There's a new number one on this year's Fortune 500 list.

High prices at the pump translated into great results for energy companies like Exxon Mobil, which knocked Walmart out of the top spot - moving it to number two.

Chevron, Conoco and General Motors follow.

St. Louis is fortunate to have 9 companies mentioned on the Fortune 500 list, with Express Scripts ranking the highest of them. Others include Monsanto, Emerson, Reinsurance Group of America, Peabody Energy, Ameren, Charter Communications, Graybar Electric and Centene.

Fortune Magazine ranks companies based on revenue -- not other measures like profits or market capitalization.

Last year, the top five companies on the list were Wal-Mart, Exxon Mobil, Chevron, Conoco Phillips, and Fannie Mae.

The list is usually a reflection of the economy.

Click here to see Fortune 500's full listfor 2012.