Wal-Mart (WMT) shares climbed 3% Thursday after the giant retailer surprised Wall Street by boosting its earnings estimate for the third quarter, despite tepid sales.

The Bentonville, Ark., company said it now expects to make 68 cents to 69 cents a share for the quarter, up from its previous forecast of 62 cents to 65 cents a share. Analysts polled by Thomson Financial expected earnings of 63 cents a share.

The company said it had improved expense controls at its Wal-Mart Stores division, which expanded profit margins. That helped offset relatively meager sales growth.

Wal-Mart said same-store sales rose 1.4% from a year ago in September, at the lower end of its forecast for a 1% to 3% rise. Analysts expected a 1.8% increase in same-store sales, or sales at stores open at least a year.

Sales in established Wal-Mart stores inched up 0.8%, and those at warehouse-club operator Sam's Club jumped 4.4%.

"Overall, apparel and home remain soft. Company research reinforces that customers remain concerned about their finances, especially the cost of living," Wal-Mart said. "In addition, unseasonably warmer weather in much of the country, coupled with tighter consumer spending, negatively impacted key seasonal categories."

The report came as many retailers reported sluggish sales for September, including Wal-Mart rival Target (TGT) and department-store chains like J.C. Penney (JCP) and Macy's (M) . While several chains attributed the drop to warmer-than-average weather, the companies are also dealing with inventory missteps and the threat of tighter consumer spending.