Even the biggest Websites do not have the reach of advertising networks. Google, viewed by 70% of US Internet users, was just ninth on the list of top ad-supported media properties and ad networks in July 2008 in terms of reach, according to comScore Media Metrix.
Google, Yahoo! and other portals are keenly aware of the power of ad networks, which is why they have networks of their own.
The Interactive Advertising Bureau (IAB) and Bain & Company recently completed a benchmarking study of online ad networks, and found two main reasons for the networks' rise. First, available ad space is growing because of inadequate pricing tools and inventory management discipline, leading publishers to seek out ways to get some type of return on unsold ads.
The other reason online ad networks are growing is through being perceived as cost-effective; large marketers view the networks as both a shortcut to greater buying scale and a way to drive down CPMs.
The IAB and Bain said ad network revenues grew more than 50% in 2007 over 2006 levels. Video ads were especially desirable, with CPMs two to three times greater on average than display ads.
Learn the role of online ad exchanges in the growing digital marketing landscape. Read eMarketer's US Online Advertising: Resilient in a Rough Economy report.