CANNES, France — WPP’s GroupM recently declared it would no longer buy advertising spaces from open trading exchanges from next year. The global boss of GroupM’s data-driven unit backs that strategy.

“It’s our ambition to not buy any media in an open marketplace,” says Xaxis global CEO Brian Lesser.

“Our clients expects us to give them competitive advantage in the marketplace. By the end of the year, we will be completely off of exchange-traded media – which is the right goal for our clients.”

Lesser spoke with Beet.TV during the Cannes Lions International Festival of Creativity. Please find more coverage of the festival here.