Twelve major U.S. retailers reported a 3.7 percent increase in April sales at stores open at least a year, according to Thomson Reuters same-store sales index. That was less than the 4.3 percent increase Wall Street expected.

Wall Street got ahead of itself with upbeat expectations, said AlixPartners' Managing Director Steve Nevill, noting that unemployment remained high and consumers were still worried about their prospects.

"I still don't see us breaking out of this average performance until something big happens to lift consumer confidence," Nevill said.

L Brands Inc (>> L Brands Inc), which operates Victoria's Secret, said sales at stores open at least a year, were up 2 percent last month, but missed analysts' estimates at all of its major brands, including Bath & Body Works. The stock was down 1.1 percent.

Costco Wholesale Corp (>> Costco Wholesale Corporation) reported a 4 percent gain, slightly less than expected, in part because of sharply lower gas prices. Still, the warehouse club operator said sales of food and consumer electronics were good. Cost shares fell 0.5 percent

In contrast, so-called off-price chains TJX Cos Inc (>> The TJX Companies, Inc.), which operates T.J. Maxx and Marshalls, and Ross Stores Inc (>> Ross Stores, Inc.) both easily beat Wall Street targets, the latest proof that shoppers remained price conscious despite gradual improvements in the job market.

Ross raised its first-quarter profit forecast after reporting a 7 percent gain in same-store sales. Larger rival TJX Cos said same-stores sales rose 8 percent last month. TJX Cos shares added 0.6 percent, while Ross was up 0.2 percent.

Because of the timing of Easter, March sales numbers were artificially low, while April got a boost. Taken together, retail spending grew about 2 percent, roughly in line with trends in the last two years, said International Council of Shopping Centers Chief Economist Michael Niemira.

Spending is not expected to rise much faster than that in the coming months as consumers wrestle with a variety of worries, including the U.S. economy, Europe's economic problems, the debt debate in Washington and employment.

The ICSC expects same-store sales to increase 2 percent to 3 percent this month.

Gap Inc (>> The Gap Inc.), the last company in the Thomson Reuters Same-Store Sales Index to report, will release its numbers after the stock market closes.

The S&P Retail Index <.SPXRT> was up 0.1 percent at midday.

LOTS OF DISCOUNTING

With the weather cool in much of the country in April, many shoppers' delayed purchases of spring clothing.

Janney Capital Markets analyst Adrienne Tennant said in a note this week that retailers were more aggressive in offering discounts in April, but things eased at the end of the month, suggesting stores had not over-ordered and making it likely they would avoid panicked markdowns.

Fred's Inc (>> Fred's, Inc.) and Cato Corp (>> Cato Corp) each reported slim sales gains last month.

Retailers that don't report monthly sales posted disappointing numbers. Ann Inc (>> Ann Inc), the parent of the Ann Taylor chain, and Wet Seal Inc (>> The Wet Seal, Inc.) each recorded declines in same-store sales for the first quarter.

Last week, drugstore chain Rite Aid Corp (>> Rite Aid Corporation) said same-store sales fell 4 percent in April, largely as many lower-cost generic drugs came to market in the last year. Larger rival Walgreen Co (>> Walgreen Company) reported a modest 1.2 percent rise, hurt by a drop in sales of general merchandise.

Others did manage to buck the trend. Teen retailers The Buckle Inc (>> The Buckle, Inc.) and Zumiez Inc (>> Zumiez Inc.) reported much better-than-expected April sales on Thursday, and American Apparel Inc (>> American Apparel Inc.) had a 3 percent gain. Zumiez shares jumped nearly 4 percent, while Buckle added 1.3 percent.

As previously announced, TJX and Ross will no longer report monthly sales after April. That will leave 11 U.S. chains reporting monthly sales, down from a peak of 68 in 2006. In the years since, big names such as Macy's Inc (>> Macy's, Inc.), Wal-Mart Stores Inc (>> Wal-Mart Stores, Inc.) and Best Buy Co Inc (>> Best Buy Co., Inc.) have dropped out of the same-store sales index.

(Additional reporting by Jessica Wohl in Chicago; Editing by Maureen Bavdek and Jeffrey Benkoe)

By Phil Wahba