• by Tyler Loechner , Staff Writer @mp_tyler, April 2, 2014

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.