ChannelAdvisor (ECOM +0.4%) clients saw a hefty 40.4% Y/Y increase in their July Amazon (AMZN +3.1%) same-store sales. That's up from June's 34.4%, and is easily the highest rate seen in the last 12 months. 38.2% of tracked Amazon GMV was fulfilled by Amazon, up from 29.8% a year ago.
On the other hand, eBay's (EBAY -1.1%) same-store growth fell to 9.7% from June's 12.3% Auctions -8.2%, fixed-price +12.8%, Motors +8%. ChannelAdvisor sees the numbers as a sign eBay "continues to face headwinds" from Google algorithm changes and a May data breach.
Search ad-driven same-store sales, which are dominated by Google (GOOG +1.3%) AdWords, fell to 7% from June's 20.4%. While average order value (AOV) grew 6% and conversion rates 8%, mobile growth led ad prices (cost per click) to fall 7%.
Google Shopping/product listing ads (previous) continue to perform well: They saw 40.8% same-store growth, down a bit from June's 47.8%. Conversion rates fell 9.5%, but AOV grew 8.9% ChannelAdvisor thinks mobile is hurting conversion rates, and that Google is "counteracting that by showing higher-priced items."