Research firm comScore says U.S. online sales this holiday shopping season are up 15 percent so far compared to last year.
The Reston, Va., company says shoppers have spent $30.9 billion online from Nov. 1 through Dec. 16, up from $26.9 billion at the same point last year.
Online sales surpassed $1 billion on four days last week, which comScore expects to be the heaviest week of online shopping this holiday season.
Cyber Monday, the Monday after Thanksgiving, remains the biggest online shopping day in history, with $1.25 billion in sales.
The company says spending will start to slow as Christmas draws closer.
(Copyright 2011 by The Associated Press. All Rights Reserved.)