An ad exchange is a technology platform that facilitates the buying and selling of online media advertising inventory whose prices are determined through bidding from multiple ad networks. The approach is technology-driven as opposed to the historical approach of negotiating price on media inventory. This represents a field beyond ad networks as defined by the Interactive Advertising Bureau (IAB), and by advertising trade publications such as Advertising Age.
The major ad exchanges include:
- AdECN, which is owned and was purchased by Microsoft in August, 2007 (Microsoft officially switched from AdECN to AppNexus for its real-time bidding needs- three years after it acquired it) This change finally retired the AdECN platform.
- RightMedia, which is owned and was purchased by Yahoo! in April 2007;
- DoubleClick Ad Exchange, which is owned by DoubleClick, a Google subsidiary purchased in May 2007;