Retail websites account for more than half of the top 20 most visible advertisers in Google paid search, according to a new report from Searchmetrics.

Question answering site actually takes top spot for paid search, with Amazon and Zappos taking second and third respectively.

The findings come from a study into the top 20 most visible sites in paid search on and a similar list for the top performers in organic search.

To find out more about paid search, check out our new Paid Search Marketing (PPC) Best Practice Guide.

It includes best practice around mobile paid search, integrating paid search with other channels (including offline), and takes into account Google’s new Enhanced Campaigns function.

Due to the competitive nature of ecommerce it’s no great surprise that retail websites make up a majority of the paid search top 20, but it is interesting to note that takes fourth place.

Google uses paid search results to attract customers for its own products, such as the AdSense program and Google Chrome. 

The report also looks at the most visible sites in organic search on Wikipedia tops the list with a visibility score five times higher than Facebook in second place.

We’ve previously looked at why Wikipedia dominates organic search to such an extent, with the conclusion being that its visibility is attributable to unique and in-depth content, targeted webpages for key terms, strong domain authority and a great internal linking structure.

Amazon is the highest ranked ecommerce site at number five on the list, followed by Apple in tenth place.

Facebook and Twitter come in at second and third place in the organic visibility rankings, in part due to the massive volume of content generated on social networks every second.

The high visibility scores achieved by these sites provides a convincing argument for why brands need to build a strong presence on social networks.

The Searchmetrics’ weekly Paid Visibility score is a measure of how frequently and prominently a domain appears in paid search results based on weekly data from the search results for millions of keywords.