Webmasters started noticing sudden affect in site traffic at the end of April month. Giant websites lost top ranking in search results for the targeted/product related key phrases due to Google May Day update which happened between April 28 to May 5. After this update, some of the e-commerce websites especially product pages lost their ranking for long-tail search queries. Most of the webmasters studied about this Google algorithmic change and discussed in detail.
During this update sites like Amazon didn’t affect due to proper internal linking structure, keyword repetition, product reviews and authority backlinks. Next step, check your site status in Google Webmaster tools and notice whether product page is removed from indexing. Utilize exact targeted key phrase within product page and internal links. Follow quality backlink process to retain the top rankings for targeted keywords and implement XML Sitemap.
Google keeps tuning their search algorithm regularly to provide best results to the user. This update is permanent and implemented in Google Caffeine update.