Wal-Mart, Best Buy, others gang up on Google Wallet - CNET Mobile Watch out, Google Wallet. There's a new mobile-payment service in the works. A consortium of of retailers today announced that they have launched a mobile-commerce company, called Merchant Customer Exchange (MCX). Best Buy, Target, Wal-Mart, and Lowe's are among the many companies that have signed up for the initiative. The companies combine to generate a whopping $1 trillion in sales each year. The retailers' move could spell trouble for Google's fledgling Wallet mobile-payment app. Google Wallet runs on Android-based devices and allows customers with certain smartphones to pay for purchases from the handset. Google Wallet has so far been slow to roll out. However, until now, it was facing few competitors. With MCX on the way, Google might find it a bit more difficult to expand its offering. Google is forced to partner with merchants and credit card companies to get its service up and running. With so many major retailers signing on to MCX, they might not want to partner with Google on Wallet.