Wal-Mart has sued Visa today for $5bn, for allegedly working with large banks and fixing the transaction fees that were charged to Wal-Mart. This comes on the back of various bits of legal chicanery. Wal-Mart opted out of a $5.7bn settlement with Visa and Mastercard in December and Visa sued Wal-Mart themselves in June to prevent them from suing. [Source: BBC News]