Who is to blame for falling CPMs, and which ad network gives marketers the reach they crave?
Those questions and a stunning hiccup from Google dominated the top stories this week. Two years ago ad networks, which accounted for a meager 5 percent of the online ad inventory, didn’t garner much attention from buyers, sellers or the press. But today, with ad networks accounting for 30 percent of the web’s inventory, the story has changed. So it’s little surprise that a recent study from the IAB and Bain & Company has attracted comments from a slew of interested parties. At the heart of the issue is Bain’s finding that ad networks — particularly secondary and tertiary sellers — have driven down CPM revenue on premium content. According to the study, publishers selling their inventory through ad networks are getting CPMs between $0.60 to $1.10 — a shockingly low number compared to the $10 to $20 the same websites get by selling their inventory directly to advertisers. But whether ad networks or a surplus of inventory are to blame for the decrease in prices remains a subject of so
