CEO Mike Duke assured shareholders that the “greatest priority” is to get its revenue at stores open at least a year — a key measure of a retailer’s health — to rise again. Shoppers are focusing on groceries and little else, said Bill Simon, president and CEO of its U.S. namesake business. He noted to reporters that it’s seeing the widest swing ever in spending around when shoppers get their paychecks. That’s making Wal-Mart scramble harder to offer smaller packages for shoppers at the end of the month and alter its staff scheduling. “Customers are struggling,” he said. Rising costs in commodities are also putting more pressure on Wal-Mart, which can’t pass big price increases along to its already-stressed shoppers.