Midnight in the food-stamp economy

At 11 p.m. on the last day of the month, shoppers flock to the nearest Walmart. They load their carts with food and household items and wait for the midnight hour. That's when food stamp credits are loaded on their electronic benefits transfer cards.

"Once the clock strikes midnight and EBT cards are charged, you can see our results start to tick up," says Tom Schoewe, Wal-Mart Stores Inc's chief financial officer.

As food stamps become an increasingly common currency in a struggling U.S. economy, they are dictating changes in how even the biggest retailers do business.

From Costco to Wal-Mart, store chains are rethinking years of strategy as they watch prized customers lose jobs and turn to this benefit, the stigma of which is disappearing not just in society, but in corporate America.