CANNES — WPP’s data-centric Xaxis division has tripled in size from around 100 staff to more than 300 in its first two years, and CEO Brian Lesser says that growth suggests the future scale of highly targeted online ad buying tactics many label “programmatic”.

“Over the next three to five years, you will see that the majority of digital advertising is being traded through programmatic systems,” Lesser told Beet.TV in this interview during Cannes Lions.

Xaxis, which now manages $400 million in annual spending, exists to target consumers whether they be offline or on one of a plethora of devices. But Lesser acknowledged challenges:

“On some mobile devices, it’s difficult for us to identify audiences in an anonymous way, because we can’t sync up our cookie database. But there are strides being made to develop technologies that sit alongside the cookie or even replace the cookie that will help us identify users across devices in an anonymous and privacy-friendly way.”

Lesser was a participant in a rooftop round-table event at Cannes Lions organized by The Rubicon Project that involved the heads of the major holding company trading desks top executives.  Here is a report on session in the AdExchanger.