Xandr

Xandr is Microsoft's advertising and analytics subsidiary that emerged from one of the most dramatic consolidation stories in programmatic advertising. Originally built on the foundation of AppNexus—once a category-leading demand-side platform founded in 2007—Xandr was created by AT&T in 2018 following its $1.6 billion acquisition of AppNexus, with the ambitious vision of constructing a national TV advertising marketplace that could leverage AT&T's vast consumer data and WarnerMedia content.

Named after Alexander Graham Bell (AT&T's founder), Xandr represented AT&T's attempt to create a 'modern media business' by combining mobile services, media content, and advertising technology into a unified ecosystem. However, the integration proved challenging, with the programmatic advertising business struggling to find its place within AT&T's traditional TV advertising operations, ultimately leading to significant losses and management turnover.

The platform distinguished itself through its comprehensive ad tech stack including Xandr Invest (demand-side platform), Xandr Monetize (supply-side platform), and Xandr Curate (private marketplace), serving over 250 billion ad impressions daily with advanced real-time bidding, cross-screen reach capabilities, and sophisticated data-driven targeting across display, video, connected TV, and audio advertising formats.

Microsoft's acquisition of Xandr for approximately $1 billion in 2022 marked the end of an era, as Microsoft has since announced the shutdown of the Xandr DSP platform by March 2025, replacing it with AI-powered advertising solutions integrated into the broader Microsoft ecosystem. This transition represents the industry's broader shift away from traditional programmatic models toward more conversational and AI-driven advertising experiences, effectively closing the chapter on what was once AppNexus's pioneering role in programmatic advertising.