ComScore recently released its February 2014
“Top 50 U.S. Desktop Web Properties” ranking, and Joe Mandese and I got a pitch from one of the ranked companies touting their place on the “DSP/SSP/Ad Exchange Entities”
list.
Except there was a caveat. Just three companies were on that particular list -- Rubicon Project, engage:BDR, and Fulcrum5.
There was a separate list -- Top 20 Ad Networks/Buy
Side Networks -- which housed names such as Criteo, Casale Media, RadiumOne, and Rocket Fuel.
It got us thinking about what the ranking actually was and how they rank DSP/SSP/Ad Exchanges.
Unfortunately, we don’t really know what qualifies a company for the DSP/SSP/Ad Exchange list versus the Ad Networks/Buy Side Networks list.
What we did learn was that the rankings (for
both lists) require opt-in participation from the providers; it's the only way comScore can measure the audiences. That’s just 
something to keep in mind, because it
means the rankings aren’t comprehensive.
Making things even more Twilight Zone-y is the fact comScore acknowledges that separate lists are nothing more than a semantics dance. You just
need to read the fine print.
See those two stars (**) next to each company’s name in the image above? Now read the fine print:
So...why aren't they all just on one list?
Even comScore couldn't help us answer that one.