NEW YORK (AP):

The back-to-school shop-ping season had a disappointing start in July as Americans rattled by a weakeninghousing market and other financial pressures stayed away from stores and malls.

As merchants reported sluggish monthly sales results yesterday, the weakest performers were mall-based apparel chains, particularly teen merchants like Pacific Sunwear of California Inc. and Wet Seal Inc. Wal-Mart Stores Inc. posted a slim gain but warned that its increased discounting are hurting profit margins.

Among the few standouts were J.C. Penney Co. and Costco Wholesale Corp., both of which beat expectations.

"Overall, July sales were negatively impacted by soft mall traffic," said Ken Perkins, president of RetailMetrics LLC, a research company in Swamp-scott, Massachusetts. "The consumer is holding up, but certainly feeling the pinch of the housing market and higher gasolene price."

According to Thomas Financial, 15 retailers beat expectations, while 29 missed estimates.

July's results extended the slowing sales trend retailers have experienced since February as consumers are forced to pay more for food and gas. The slumping housing market and a widening credit crunch, both of which have made the stock market turbulent, are also making consumers shy about spending.

Still, the picture was made more complicated because of some quirks in the retail calendar. Sales for the first week of August, a key back-to-school week, were reported in this year's July period, which did help July figures but should reduce business for August. And results were depressed by a shift in a tax free sales week to August in two critical states, Florida and Texas, which analysts say helped delay shopping.

Analysts also point out that an increasing number of schools are starting classes later, delaying back-to-school purchasing. Teens usually wait to do the bulk of their shopping until after school starts because they want to see what their friends are wearing.