U.S. holiday sales will fall more than forecast after recession fears kept shoppers from spending in the last weekend before Christmas, a retail trade group said.

Sales in November and December may drop as much as 2 percent, the International Council of Shopping Centers (ICSC) said today, more than the previously projected 1 percent. That would make it the worst Christmas sales season in at least four decades.

U.S. shoppers have been grappling with a recession, tightening credit and the loss of 1.91 million jobs through November. Retailers, including Macy’s Inc. and AnnTaylor Stores Corp., have responded with steepened markdowns, which may erode profit margins in the fourth quarter, the most important of the year for retailers.

“At this point in the season, you just need to move the inventory off the shelves and convert it to cash,” Adrienne Tennant, a retail analyst at Friedman, Billings, Ramsey & Co. in Arlington, Va., told Bloomberg Television.

Sales at stores open at least a year declined 0.6 percent in the seven days through Dec. 20 from a year earlier, the ICSC and Goldman Sachs Group Inc. said today in a joint statement. November sales fell a record 2.7 percent.

Same-store sales for November and December combined may decrease 1.5 percent to 2 percent, ICSC chief economist Michael Niemira wrote in an e-mail to Bloomberg. That would be the largest drop since at least 1969, when the New York-based trade group started tracking data. Some investors consider comparable-store sales the best measure of results because they exclude the effect of store openings and closings in the past year.