Holiday sales are hopping online, several new studies indicate.E-commerce sales hit $2 billion last week, the largest weekly amount ever recorded, ComScore Networks reported on Tuesday. Meanwhile, Monday was the biggest online sales day of the year, with sales reaching $367.05 million, according to BizRate.com. While ComScore's numbers include sales of travel, BizRate's do not. "E-commerce is doing great," said Helen Malani, a spokeswoman for Los Angeles-based BizRate. Even so, it's unclear whether online sales will meet analysts' expectations. ComScore, for instance, projected that nontravel, nonauction sales in the fourth quarter would grow 27% over the same period last year to $13.8 billion. Thus far, such sales to date have grown about 24% to $9.3 billion. The shortfall is nothing to worry about, said Dan Hess, vice president of ComScore. "The early weeks of the quarter showed growth rates that were not consistently as strong. Now that the season's in full swing, we're going to see that gap closing fast," Hess said. Meanwhile, BizRate projects that e-commerce sales are already in line with its projections. The research firm had forecast that excluding travel, auctions and event tickets, online sales in the fourth quarter would grow 35% over last year to $16.8 billion. For the period of Nov. 1 to Dec. 9, sales have totaled $8.4 billion, up 43% from the same period last year. The bright outlook for e-commerce comes against a cloudy time for traditional retailers. Bricks-and-mortar retailers reported mixed November sales results last week, with companies such as the Gap ( GPS) posting significant improvements, while others such as Wal-Mart ( WMT), Sears ( S) and Target ( TGT) posting disappointing or decreasing sales at comparable stores. E-commerce's success may be coming, at least in part, at the expense of traditional retailers, the new studies indicate. A survey of online shoppers by the National Retail Federation's Shop.org indicates that 35% of them plan to spend more money online this holiday season compared with last year, while 26% expect to spend less. In contrast, only 15% planned to spend more at traditional stores, while 46% expected to spend less.