Brian Lesser

Brian Lesser is one of the most consequential figures in the history of programmatic advertising, currently serving as Global CEO of WPP Media (formerly GroupM), the world's largest media investment group. Appointed to the role in 2024, Lesser brings decades of experience building and scaling data-driven advertising businesses to lead WPP's unified media operation, which manages hundreds of billions of dollars in media spend on behalf of some of the world's largest advertisers. His appointment signals WPP's commitment to transforming GroupM into a more technology-forward, data-centric organization. Lesser's career is defined by his ability to build category-defining AdTech businesses from the ground up. He founded Xaxis, GroupM's programmatic technology and data platform, which became the world's largest programmatic media company and pioneered the concept of outcomes-based programmatic buying. He later served as CEO of Xandr, AT&T's advanced advertising and analytics company (formerly AppNexus), where he led the integration of AT&T's vast data assets with a world-class programmatic infrastructure to create a next-generation advertising marketplace. Across his career, Lesser has been a driving force behind the industry's shift from traditional media buying to data-driven, technology-enabled advertising. His work at Xaxis helped legitimize programmatic buying for major brand advertisers, while his leadership at Xandr pushed the boundaries of identity-based targeting and connected TV advertising. As Global CEO of WPP Media, he is now positioned to influence the future of the entire media agency model at a time of profound disruption from AI, privacy regulation, and the fragmentation of media consumption.

Last updated Sep 26, 2026 by ATDb automated enrichment