SAN FRANCISCO -- ChannelAdvisor said on Tuesday that client sales on eBay's (EBAY) online marketplace grew faster than on Amazon's website during the crucial first five days of the holiday shopping season.

ChannelAdvisor reported clients sales on eBay.com grew 55.2 percent on Cyber Monday, compared to the same day last year. For the five-day period from Thanksgiving through Cyber Monday, which ChannelAdvisor calls the "Cyber Five," client sales on San Jose-based eBay rose 38.3 percent compared to the same days in 2011.

ChannelAdvisor said client sales on Amazon.com jumped 42.4 percent on Cyber Monday compared to a year earlier. Over the "Cyber Five," client sales on Amazon.com rose 37.7 percent, the firm said.