Wal-Mart says it is asking some stores to schedule workers for fewer hours, although it says the directive is only being given to stores that are assigning more hours than they were expected to. The world's largest retailer said the instructions apply only to a small number of its 4,500 U.S. locations that are scheduling workers for more hours than expected.Wal-Mart said Monday it spoke to store managers about controlling costs earlier this month at a holiday-season planning meeting. Managers who have been scheduling workers for too many hours were reminded to schedule closer to their allotted hours.Wal-Mart's second-quarter profit fell 15 percent, partly because of pay raises, efforts to overhaul its stores, and investments in its online operations. The changes did help its sales, however.The Bentonville, Arkansas-based company raised its minimum wage to $9 an hour in April and plans to raise it to $10 an hour by February.As of Jan. 31, Wal-Mart had about 1.4 million employees in the U.S. It did not say how many of them might be working fewer hours.