Wal-Mart Stores Inc. is winning the lowest borrowing costs thisyear as its AA credit rating offsets challenges ranging from acorruption probe to reports of thinly stocked shelves.

The world's largest retailer, which has $5 billion of debtmaturing through October, yesterday sold an equal amount of bondsin a four-part offering that included the lowest coupon onthree-year notes in 2013, according to data compiled by Bloomberg.Wal-Mart's sale adds to a supply of AA-rated debt that has declinedto 11 percent of the $4 trillion U.S. corporate market from 18percent three years ago.

Wal-Mart, whose annual free cash flow exceeds the market valuesof about half the companies in the Standard & Poor's 500 stockindex, is succeeding in the bond market even after forecastingquarterly same-store sales won't improve from a year earlier. TheBentonville, Arkansas-based retailer is also contending with afederal investigation into whether it systematically bribed Mexicanofficials and customer complaints of deteriorating service.