Walmart has changed its stocking pattern after noticing that sales spike at the first of every month, when food stamps kick in for the millions of poor families around the country. Midnight shopping has become commonplace, as parents stock up on necessities like baby formula the exact minute government checks are renewed. A Walmart executive says the pattern paints a portrait of the current U.S. economy. "And if you really think about it," executive Bill Simon said, "the only reason somebody gets out and buys baby formula is they need it and they've been waiting for it. Otherwise, we're open 24 hours, come at 5 a.m., come at 7 a.m., come at 10 a.m. But if you're there at midnight you're there for a reason." So now Walmart puts out bigger boxes—especially with diapers and baby food—at the beginning of the month, and smaller ones toward the end, when family funds begin to run dry.