NEW YORK — Wal-Mart Stores, the worlds biggest retailer, said the weak global economy continues to batter its low-income shoppers.The chain cut its annual profit and revenue outlook for the year Thursday after its second-quarter results missed Wall Street estimates. The companys stock fell nearly 3 percent. The sober assessment adds to worries about consumer spending that arose when Macys lowered its profit expectations for the year after reporting disappointing results and Kohls did the same, even after posting solid results. Wal-Marts results are even more troubling because the chain is considered an economic bellwether, accounting for nearly 10 percent of nonautomotive retail spending in the U.S.Wal-Marts latest performance appears to show that many people continue to struggle in the U.S. and abroad. In the U.S., while jobs are easier to get and the housing market is gaining momentum, these improvements have not been enough to get Americans to spend. On top of that, Wal-Mart said Americans continue to struggle with a 2-percentage-point increase in the Social Security payroll tax since Jan. 1. Chief Financial Officer Charles Holley told reporters that the top three concerns among customers are jobs, food costs, and gas and energy prices. The retail environment remains challenging in the U.S. and our international markets, as customers are cautious in their spending, Holley said, noting a reluctance among customers to spend on items like flat-screen TVs. The Bentonville, Ark.-based retailer said second-quarter net income rose 1.3 percent to $4.07 billion, or $1.24 a share, for the three months that ended July 31. That compares with $4.02 billion, or $1.18 per share, a year earlier. Excluding a one-time charge for a certain nonincome tax matter, earnings per share would have been $1.25. That matches Wall Streets estimates.Net sales rose 2.4 percent to $116.2 billion. That figure excludes membership fees from its Sams Club division. The number came in below estimates of $118.09 billion in net sales, according to FactSet research firm.U.S. Wal-Mart stores, which account for 59 percent of the companys total sales, posted the second straight quarter of declines in a key revenue figure after six consecutive quarters of increases. Revenue at stores open at least a year considered an important measure of retail performance fell 0.3 percent at Wal-Marts U.S. namesake business. Thats below the 0.7 percent gain expected by analysts. Adding in Sams Club and international stores, revenue at stores open at least a year was flat compared with a year ago. It rose 1.7 percent at Sams Club. Overall, total sales increased only modestly for Wal-Marts U.S. business, Sams Club and its international division for the latest quarter. Wal-Marts U.S. division posted a total sales increase of 2.1 percent to $68.73 billion, while Sams Club saw a 2.6 percent increase to $14.53 billion. At Wal-Marts U.S. stores, clothing did well as the discounter has refocused on basics like socks and no-frills jeans that its shoppers need. During a call with reporters, Holley said it is too early to discuss how the back-to-school business is faring. But he said hes encouraged by early sales of childrens clothes. Still, sporting goods and entertainment products like toys saw declines in the quarter. Cooler weather earlier in the spring hurt merchandise like water toys and pools. And the lack of innovation in the electronics area limited business. But Holley told reporters that results were also hurt because shoppers are hesitant to spend on items they really dont need. In the grocery aisles, Wal-Mart saw a slight decline in sales. A big factor was lower-than-expected inflation, or even deflation in certain cases, such as with snacks and frozen food. But as Wal-Mart saw in the first quarter, shoppers traded down to cheaper products to save money. The companys international business had an increase of 2.9 percent to $32.96 billion. Doug McMillon, president and CEO of Wal-Marts international division, said that during the first half of the year, consumers in both developed and emerging markets curbed spending a trend that will persist through 2013.Wal-Mart said it now expects total sales to rise 2 to 3 percent for the full year. The previous forecast was for growth of 5 to 6 percent. The company also took a dime per share off its full-year profit outlook, cutting it to between $5.10 and $5.30 per share from between $5.20 and $5.40. Analysts had expected $5.29 per share. Wal-Marts stock (ticker: WMT) fell $1.99 to $74.41 on Thursday.