For the third straight year, Wal-Mart Stores Incorporated is atop the Fortune 500 list of companies. The magazine`s list ranks firms based on sales figures. Bentonville-based Wal-Mart had 2003 sales of $259 billion. Four other companies based in Arkansas are also on the list. Springdale-based Tyson Foods, the world`s largest meat producer, is Number 72. Among companies in Little Rock, Alltel Corporation is Number 251 and Dillard`s is Number 258. El Dorado-based Murphy Oil came in at Number 340. In terms of profits, Exxon Mobil was first on the Fortune list with $21.5 billion in earnings. Wal-Mart, which has the lower profit margins of the retailing industry, had $9 billion in earnings.