NEW YORK (AP) — A flurry of post-Christmas shopping helped sales surge in the last week of December, according to a mall trade group’s report released today. Increased gift card use, mild weather and a federal holiday on Monday all contributed.

Sales at stores open at least one year rose 5.3 percent during the week ended Saturday compared with the same period a year ago. That report comes from the International Council of Shopping Centers and Goldman Sachs Weekly Chain Store Sales Index, which estimates sales for 24 major stores like Target and Costco.

Revenue at stores open at least a year rose 1.2 percent for the week ended Saturday compared with the previous week, according to the index.

The metric is considered a key gauge of a retailer’s health because it excludes results from stores recently opened or closed.

As a result of the Christmas week surge, the group increased its December sales growthestimatetoa4percent to 4.5 percent rise. Previously, the council expected December sales to rise by 3.5 percent to 4 percent.

Another report

Major retailers are set to release their final figures for the month on Thursday, but the big concern is how aggressive discounting and other incentives like earlier store openings and free shipping affected merchants’ profits.

“ The concern going into the season was that the profitability wouldn’t be as high as a year ago,” said Mike Niemira, chief economist at the International Council of Shopping Centers. “I suspect adjustments will have to be made.” That could range from some stores closing unprofitable locations to changes in marketing strategy.

For the November and December period combined, revenue at stores opened at least a year is now expected to rise by 3.8 percent, up from the original 3.5 percent, says Niemira.