Ford, GM Edge Lower in Fortune 500

General Motors Co. ranks seventh among American companies in the 2013 Fortune 500 list, down from fifth place last year.

Ford Motor Co. slipped from ninth to 10th in the rankings, which are based on annual revenue.

Wal-Mart Stores moved up a step to capture the top spot on the 2013 list, followed by Exxon Mobil (2), Chevron (3), Phillips 66 (4), Warren Buffett's Berkshire Hathaway (5) and Apple (6).

Among auto suppliers, Johnson Controls (67) placed highest, followed by Goodyear (137), Cummins (160), TRW (173) and Lear (187). Truckmaker PACCAR ranked 168th.