Wal-Mart, the largest US retailer, on Thursday launched its first new store concept in a decade with the opening of four small grocery stores in the Phoenix, Arizona area, which are are less than a tenth of the size of its huge Supercenters.

The new 15,000 sq ft stores are painted in plum-purple and trade under the Marketside logo, rather than the Wal-Mart name. They mark the retailer's test of a small neighbourhood store format that has been the focus of Tesco's US expansion with its new 10,000 sq ft Fresh & Easy stores.