The idea of an ad exchange is similar to a stock exchange, where buyers and sellers work through a broker. Similarly, AdECN does not do business directly with advertisers or publishers; it works instead with ad networks, ad brokers, and a few ad agencies that maintain relationships with buyers and sellers, acting as a network themselves.
If you're keeping score, that leaves newcomer ContextWeb and its ADSDAQ exchange as the last independent player standing in the ad exchange space.
Optimising Digital Marketing Campaigns with Search, Social and Analytics
At SES London (9-11 Feb) you'll get an overview of the latest tools, tips, and tactics in Paid, Owned, Earned, Integrated Media and Business Intelligence to streamline your marketing campaigns in 2015. Register by 31 October to take advantage of Early Bird Rates.