(Wal-Mart article updated with analyst commentary.)NEW YORK ( TheStreet) -- Wal-Mart named a new chief merchandising officer on Friday. The discount giant selected Duncan Mac Naughton to fill the role effective immediately. The former head of merchandising, John Fleming, stepped down on Aug. 1, after serving the company for 10 years. Mac Naughton will oversee all merchandise categories across more than 3,700 stores in the U.S. business, reporting to CEO Bill Simon. Mac Naughton joined the company in 2009 as chief merchandising officer for Wal-Mart Canada. In October 2010, he was named executive vice president of merchandising for Wal-Mart U.S., where he was responsible for consumables, health and wellness, and Walmart.com. Before joining the company, Mac Naughton held leadership roles at Kraft Foods ( KFT), H.E. Butt Grocery and Albertson's. He also served as executive vice president of merchandising and marketing at Supervalu ( SVU). While Mac Naughton appears to have all the credentials necessary to fill the role, Wall Street may have been looking for more of surprise. "We would have viewed more favorably fresh eyes on a business that has not been working as well as it should be; a shakeup of sorts from the status quo of aggressively promoting food and consumables, while willing to lose share in margin enhancing departments," Wall Street Strategies analyst Brian Sozzi, wrote in a note. Wal-Mart postponed hiring a new chief merchandising officer this fall, instead appointing four new heads of product to adopt these responsibilities. The appointment of a new CMO comes at a critical time, as Wal-Mart grapples with five quarters of declining U.S. same-store sales. While the economic downturn lessened the spending power of its core customer, lackluster sales can also be blamed on internal mistakes.