Norman characterizes exchange-based media buying as a subset of audience buying, which he says extends back decades and is not only about digital.
To illustrate, he observes that as with targeted digital ads, the splashiest TV inventory such as that associated with American Idol and the Super Bowl represent an insignificant wedge of available impressions.
"As a percentage of the spots and inventory they're the tiniest fractions. The difference comes when you are looking at something that is absolutely content-specific that would require a greater activation around the product. You don't just buy the Super Bowl, you do many other activations around it."
However: "There are very many, the vast majority that you don't do other activations around," he says. "That vast majority are what we would call audience buying in digital."
GroupM's Xaxis unit is the agency network's executional arm for exchange-traded digital buys around the world, and naturally its work extends to many other WPP operating agencies as well. It's a close working relationship. Norman sits on the board of Xaxis, and Xaxis CEO Brian Lesser sits on GroupM's global digital executive committee.