• by Sarah Mahoney  @mahoney_sarah, August 16, 2011

While blaming economic uncertainty for a bigger-than-expected decline in its U.S. sales, Walmart raised its earnings forecast for the full year, and says it is encouraged by sales gains in apparel and hardlines.

For the second quarter of its fiscal year, the Bentonville, Ark.-based company says total sales rose to $108.6 billion, an increase of 5.5% from $103 billion in the same period last year. Net income rose 5.1% to $3.94 billion, from $3.75 billion in the year-ago period.

But on a same-store basis, sales in its U.S. Walmart stores fell 0.9%, when observers had been expecting a decline of just 0.6%. At Sam's Club, same-store sales rose 5%. (For the first six months of the year, Walmart U.S. sales declined 1%, while Sam's Club sales rose 4.6%.)

In the company's earnings release, Bill Simon, Walmart U.S. president and CEO says that the company is encouraged by continuing positive results in its grocery and health and wellness businesses, which account for roughly two-thirds of its sales, and that it is also seeing improvement in both hardlines and apparel sales.

"We remain concerned about the economic pressure on our customers and the uncertain impact it can have on their shopping behavior. With this volatility, it is as important as ever to deliver on Walmart's one-stop shopping promise for broad assortment and every day low prices," he says.