GroupM
RebrandedLondon, England, United Kingdom · Founded 2003
10001+ employees
Sourced & current · updated Oct 14, 2026Website
GroupM, now rebranded as WPP Media, was a U.S.-based media business owned by the multinational holding company WPP plc and was the world's largest media buying agency as of 2023.
Where they sit
Stack tier: Core Platforms (S)
Attribution & AnalyticsMarketing AgencyProgrammatic Platform
Formerly the world's largest media investment group by spend; rebranded as WPP Media in 2025, retaining its position as the dominant global media buying and planning entity within WPP plc.
Ownership
Parent: WPP plc
Subsidiaries