Check out these stats from SEW:
Some new and amazing numbers released today show that search sponsored links from eBay, Shopping.com, and InterActiveCorp made up 34 percent, or nearly 13 billion, of online advertising impressions for a one week period.
Update: In the comments Chris points out we read the release wrong, it’s 34% of ALL ad impressions are search/paid links, not that 34% of search impressions are those three companies….