Wal-Mart Stores Inc. (NYSE: WMT) partnered with American Express Co. (NYSE: AXP) to offer a reloadable prepaid card to customers. Shares of prepaid card company Green Dot Corp. (NYSE: GDOT) plummeted $2.60 to $10.25. Shares of Wal-Mart edged up 4 cents to $75.17 while American Express stock added 6 cents to $58.62.