By Brad Dorfman

CHICAGO (Reuters) - U.S. retailers from Macy's to Costco posted much weaker-than-expected sales for November as shoppers focused only on big bargains at the start of the key holiday selling season.

The Thomson Reuters same-store sales index rose 0.5 percent for the month, falling far short of Wall Street expectations for a 2.1 percent increase. Many retail shares traded lower on Thursday after the reports, led by declines for teen and children's store chains. The Dow Jones Retail Index was down 0.65 percent <.DJUSRT>.

Analysts warned retailers not to expect December to rescue the holiday season, as tight credit and high unemployment dim hopes for a consumer recovery.

"This might be another season where it is a fight for share of wallet versus total increase in spending," said Chris Donnelly, a partner in Accenture's <ACN.N> retail practice. "It's pretty clear this is not a consumer who is going to be buying a lot of full-priced products."

Many retailers said the weak sales were in line with their expectations and that margins should remain intact due to inventory cuts and other cost saving measures.

"The thing we're not seeing is profit warnings," said Brian Girouard, global leader of Capgemini's consumer products and retail practice. "The analysts are disappointed and the stockholders are a bit disappointed as well, but ... it's going as planned as far as the retailers are concerned."

For example, Victoria's Secret owner Limited Brand Inc <LTD.N> forecast a low-to-mid-single-digit decline in December same-store sales, but said it would offer fewer promotions.

But retailers could still blink to attract more sales.

"If you see someone get a little bit more promotional ... other retailers will react because they have no choice," Barclays Capital analyst Robert Drbul said.

Macy's <M.N> shares fell 3.2 percent in morning trading, while Costco declined 3 percent. Among teen retailers, Aeropostale <ARO.N> dropped 11.3 percent after forecasting quarterly results that could miss analysts' estimates, while disappointing monthly results from Abercrombie & Fitch <ANF.N> sent its shares down 7 percent.

For a graphic on November sales, click http://link.reuters.com/ryb84g.

LOTS OF MISSES

A total of 81 percent of retailers tracked by Thomson Reuters missed estimates, including Costco Wholesale Corp <COST.O>, Children's Place <PLCE.O> and Walgreen Co <WAG.N>.

Over the U.S. Thanksgiving weekend that began on November 26, shoppers focused mostly on promotions and made few impulse purchases as concerns about the economy remain top-of-mind.