It may sound odd, but it seems to me that there had to be more than 123.6 billion display ads served last month.

Why? Well, we served around 35 billion with Yield Manager. While some of those ads do end up on the portals, webmail apps, and large publishers like Myspace, I think there are significantly more ad impressions out there that aren’t being reported here. I’m not even thinking about text ads and other hybrid forms of ads either.

The data is from Nielsen//NetRatings, which is well-respected, but from what I know, it just seems well short of reality.