Brian Lesser currently serves as the Chief Executive Officer of GroupM since September 2024 and is also a Board Director at Ogury from May 2023. Previously, Brian held the position of Chairman and CEO at InfoSum until September 2024 and was the CEO of Xandr at AT&T from October 2017 to September 2020. Earlier roles include CEO of North America at GroupM, Board Director at AppNexus, and Global CEO of Xaxis, among other positions in various media and advertising companies. Brian Lesser holds an MBA from Columbia Business School and a BA from the University of Pennsylvania.