roy walton chairman of the board at walmart says "this leadership change comes at a time of strength and growth." a morningstar analyst had this to say about the change at the top of the world's largest retailer. "there is formidable competition from new companies like amazon and even costco and so that's something that has to be on their radar but its not something thats new and i think that they've still got a lot of the same members in place on their executive team to keep managing the company going forward." but to some the timing is troubling. news of a ceo shift is happening just ahead of the critical holiday shopping season. walmart is already offering black friday deals online and is joining the ranks of retailers opening at 6pm "on thanksgiving--as workers at walmart and other stores and restaurants lament low wages. "we want wal-mart and corporate wal-mart to say 'we can do better, we can treat our employees better.'" one reason why wall street may be applauding walmart-- is the retailer is stepping up plans to expand in china. the world's second-largest clothing retailer p