Home Agencies Brian Lesser Is The New Global CEO Of GroupM

Brian Lesser Is The New Global CEO Of GroupM

SHARE:

If you were wondering whether Brian Lesser was planning to take some time off after handing the CEO reins of InfoSum to Lauren Wetzel last week – here’s your answer.

On Wednesday, WPP announced that Brian Lesser is the new global CEO for GroupM, which houses ad buying agencies, including Mindshare, EssenceMediacom and Wavemaker.

Lesser fills the shoes previously occupied by Christian Juhl, who is stepping down from the role after five years to take on a new position as WPP’s president of corporate development.

Juhl will stay in his current job until September to help with the transition.

This is a homecoming for Lesser, who spent two years as CEO of GroupM North America between 2015 and 2017. He was also the founding CEO of Xaxis, WPP’s programmatic trading desk, which he helmed between 2011 and 2015 and grew into a billion-dollar business. He launched the Media Innovation Group within GroupM, which included the development of one of the earliest data management platforms. 

But Lesser first started his career at WPP as the ad tech product guy when he came on board after the holding company acquired 24/7 Real Media in 2007.

According to Lesser, when he was interviewed on the first-ever episode of the AdExchanger Talks podcast in 2016, his job at GroupM back in the day was to “transform [it] to be much more about gathering data about consumers, because that’s where our leverage is going to come from in the future – and that’s how we’re going to drive performance for clients.”

No doubt, his ethos remains the same today.

“Brian is one of the industry’s most highly regarded executives with a track record of success in data- and technology-driven marketing,” WPP CEO Mark Read said in a release. “Brian not only knows GroupM inside-out, but also has a strong vision for the future of the business.”

Between his previous stints at WPP, Lesser was also the CEO of AT&T’s advertising and analytics division and was there when AT&T bought AppNexus in 2018. Lesser had served on the AppNexus board of directors for years while he was CEO of Xaxis, representing WPP, which was an early investor in AppNexus. 

Subscribe

AdExchanger Daily

Get our editors’ roundup delivered to your inbox every weekday.

But AT&T later sold AppNexus (which by that point was called Xandr) to Microsoft in 2021, after the telco’s vision for launching a data-driven media business failed to take flight. 

But Lesser had already exited AT&T before the Microsoft deal. He took the chairman and CEO role at data clean room provider InfoSum.

And now, back at GroupM, he has the top job at an agency holding company that manages more than $60 billion in annual media spend.

He has his work cut out for him, though.

During the first quarter, WPP’s revenue in North America declined by 5.2%, a reflection, the company told investors, of WPP’s relatively large exposure to technology clients, its loss of Pfizer’s business and “client assignment losses at GroupM.”

In October, GroupM announced that it was parting ways with Kirk McDonald, who had served as CEO for GroupM North America for three and a half years.

Must Read

Why 2025 Marked The End Of The Data Clean Room Era

A few years ago, “data clean rooms” were all the ad tech trades could talk about. Fast-forward to 2026, and maybe advertisers don’t need to know what a data clean room is after all.

The AI Search Reckoning Is Dismantling Open Web Traffic – And Publishers May Never Recover

Publishers have been losing 20%, 30% and in some cases even as much as 90% of their traffic and revenue over the past year due to the rise of zero-click AI search.

No Waiting for May – CES Is Where The TV Upfront Season Starts 

If any single event can be considered the jumping-off point for TV upfronts, it’s the Consumer Electronics Showcase (CES), which kicks off this week in Las Vegas, Nevada.

Privacy! Commerce! Connected TV! Read all about it. Subscribe to AdExchanger Newsletters
Comic: This Is Our Year

Comic: This Is Our Year

It’s been 15 years since this comic first ran in January 2011, and there’s something both quaint and timeless about it. Here’s to more (and more) transparency in 2026, and happy New Year!

From AI To SPO: The Top 10 AdExchanger Guest Columns Of 2025

The generative AI trend generated endless hot takes this year, but the ad industry also had plenty to say about growing competition between DSPs and SSPs. Here are AdExchanger’s top 10 most popular guest columns of 2025 and why they resonated.

Comic: Season's Beatings

Enjoy this weekly comic strip from AdExchanger.com that highlights the digital advertising ecosystem …