eBay Inc August Sales Growth Falters, Amazon.com, Inc. Zooms

Amazon.com, Inc.'s AMZN August same-store sales grew at nearly four times the industry average, while eBay Inc EBAY appeared to falter.

Marketing service provider ChannelAdvisor Corp. said Amazon's comparable sales grew more than 45 percent in the "back-to-school" month of August, while eBay's grew a mere 5.9 percent.

Total U.S. e-commerce grew at 13.1 percent in August, ChannelAdvisor estimated.

At eBay, August auctions fell 11 percent from a year earlier while growth in fixed-price sales slowed dramatically to 6.9 percent, from July's rate of 12.8 percent.

EBay Motors, which sells parts and accessories, grew at 8.4 percent, compared with July's 8 percent.

ChannelAdvisor said eBay's golf and electronics categories showed particular weakness.

"What we are seeing is big declines in those categories for sellers with used items," ChannelAdvisor Chief Executive Scot Wingo said.

Earlier this year eBay tightened its standards for reporting sales of defective merchandise and as a consequence, "sellers of used or refurbished items are having to significantly reduce their inventory," Wingo said. At the same time Amazon added several features to embrace the used and refurb market. "We are seeing a clear share move from eBay to Amazon in this category," Wingo said.

ChannelAdvisor defines "store" in its survey as one customer selling through a particular channel.

Amazon gained 0.7 percent; eBay shares were down 2.5 percent.