American consumers jammed online shopping sites on Monday, the official start of the holiday season for e-tailers, resulting in robust sales, according to an Internet research company.

The first Monday after Thanksgiving, known as Cyber Monday, represents the first big sales surge as consumers return to their offices and click on their computers to shop.

ComScore, the research company, reported yesterday that consumers spent $733 million online on Monday, a 21 percent gain from the corresponding day a year ago. ComScore had expected that sales would exceed $700 million.

While Cyber Monday kicks off the online holiday shopping season, it is not the busiest day for retailers, according to comScore. Last year, the busiest online shopping day was Wednesday, Dec. 13, generating $667 million in sales. The Monday after Thanksgiving was actually the 12th busiest day in terms of sales for the 2006 holiday period.

ComScore said that Monday’s sales results represented an 84 percent jump from the average daily online spending totals during the preceding four weeks.

ComScore reported that the number of online buyers rose 38 percent from a year ago, but the average dollars spent per buyer were down 12 percent. In a statement, comScore’s chairman, Gian M. Fulgoni, said that he believed that deeper and broader price discounts depressed sales. He also noted that new Cyber Monday buyers tended to spend less online than returning buyers.

More than $10.7 billion was spent online from Nov. 1 through Nov. 26, representing a 17 percent gain from the corresponding days last year, comScore said.

Source: www.nytimes.com