(Reuters) - Wal-Mart Stores Inc said its U.S. chief merchandising officer was leaving the company in a management shuffle just as the crucial holiday shopping season kicks into gear.Duncan Mac Naughton, who had held the post since 2011, was departing to pursue new opportunities, Wal-Mart said on Tuesday.The move had been somewhat expected for months after Mac Naughton was passed over for the top U.S. job in favor of Greg Foran, according to two people close to the company. Mac Naughton was not immediately available for comment.The chief merchandising position is vital at any retailer since it involves oversight of product and promotional strategies.Mac Naughton was a public figure at Wal-Mart, appearing before investors and media. Two weeks ago, he laid out the company's plans for five days of promotions around Black Friday to kick off the year-end shopping season.With the holiday season already in motion, the onus is now on the store operators to execute on those plans, spokeswoman Deisha Barnett said.Foran, who heads Wal-Mart's U.S. operations, said in an internal memo provided to media that he had decided not to name a new chief merchandising officer at this time. Instead, other merchandising executives would report directly to him.Mac Naughton, who joined Wal-Mart in 2009 as chief merchandising officer of Canadian operations, struggled to lift the performance of its 4,300 U.S. stores. The company posted six straight quarters of flat or declining sales at stores open at least a year before eking out a 0.5 percent gain in the quarter ended Oct. 31.Foran had indicated he wanted to make changes to the stores. At an investor conference in October, he identified a series of "urgent agenda items" that included making sure the shelves are better stocked and bolstering the offering of fresh groceries.As part of the management shuffle, Foran said Steve Bratspies would shift from executive vice president of general merchandise to executive vice president of food, with a focus on fresh grocery offerings.Shares of Wal-Mart were down 0.5 percent at $84.96 in afternoon trading.(Reporting by Nathan Layne; Editing by Lisa Von Ahn)Join the conversation about this story Click here to read full news..