As noted, Dell has historically utilized a build-to-order approach to supply chain management with a just-in-time manufacturing model where unit pieces were manufactured and stored in inventory but were not pieced together until a consumer request was issued. While this methodology rarely affords the opportunity to maximize economies of scale, it does maintain a low inventory holding cost. In May 2007, Dell began its transition into the retail market when it began selling PCs through Wal-Mart and Sam's Club. Early in 2009, Mike Gray, supply chain director for Dell,