Cyber Monday sales were up 15 to 18 percent over last year depending on the source. Online traffic was up 43 percent from last year, says content delivery network Akamai, and online sales were up 18 percent over Cyber Monday 2010 as of 9 p.m. ET, says IBM Smarter Commerce, a Web performance analytics firm for 500 of the largest retail websites.

Online sales on Cyber Monday, which was started in 2005 by a retail trade group to encourage Americans to shop online the Monday after Thanksgiving, were up by 15 percent from a year ago, according to data from IBM Benchmark.

Matt Shay, CEO of the National Retail Federation, told USA Today that sales on Cyber Monday and over the long weekend show retail is “providing a needed shot in the arm to our nascent recovery.”