Three kinds of exchanges

I realize that in prior posts I didn't really give a diagram of the definitions of an exchange that exist in the marketplace right now. I've really been referring to my own view, which is type 2 below. The word "exchange" is super hot in the online advertising space right now, and naturally companies are trying to appropriate the good ad exchange name to market their firms.

Type 1: Exchange between Advertisers and Publishers

In this example, the exchange is simply the marketplace between advertisers and publishers – the place where the publishers bring their goods to sell and the advertisers come to buy it. I kind of think of this as an ad network, but usually the proponent of this type of exchange has some new mode of interaction that they have applied and generally it revolves around pricing transparency. Instead of an arbitrage network, the exchange model involves an auction for good and the exchange takes a percent.

Some examples here are: ContextWeb's ADSDAQ and TraffIQ (I think).

Type 2: Exchange between ad Networks

This type of exchange simply connects between aggregators of demand and supply. In other words, ad networks (but it can be other stuff too). This is the kind of exchange I've been talking about. The only company following this model that I'm aware of is AdECN, recently acquired by Microsoft.

Type 3: Hybrid Exchanges

These types of exchanges mix the two models above. They are ad networks that have evolved to accept exogenous demand and supply from other networks.

If you think about it, this model is problematic in that any ad network joining the exchange runs the risk of the exchange competing with the ad network for customers (advertisers and publishers). Examples here are Right Media Exchange and DoubleClick exchange (from what I can tell).