Xandr

Formerly a major full-stack programmatic advertising platform; now absorbed into Microsoft Advertising following the retirement of the Xandr brand in 2023.

Xandr was founded in 2018 as AT&T's unified advertising technology division, built largely on the foundation of AppNexus, which AT&T acquired that same year. The platform brought together programmatic buying, selling, and data management capabilities under one roof, leveraging AT&T's vast first-party data assets to offer premium, data-driven digital advertising solutions. Xandr positioned itself as a premium marketplace connecting advertisers and publishers through its demand-side platform (DSP), supply-side platform (SSP), and data marketplace, competing directly with the likes of The Trade Desk, Google DV360, and Magnite. In December 2021, Microsoft acquired Xandr from AT&T, integrating it into Microsoft's growing advertising business to complement its existing Microsoft Advertising offerings. The acquisition gave Microsoft a full-stack programmatic advertising infrastructure and a significant foothold in the open web advertising ecosystem. Under Microsoft's ownership, Xandr continued to operate as a distinct brand for a transitional period, serving publishers, agencies, and advertisers globally. By 2023, Microsoft retired the Xandr brand entirely, consolidating its products under the Microsoft Advertising umbrella. The Xandr DSP became Microsoft Invest (with a planned sunset on February 28, 2026), the SSP became Microsoft Monetize (rebranded in May 2024), and the curation product became Microsoft Curate. While the technology and customer relationships live on within Microsoft Advertising, the Xandr brand itself no longer exists as a distinct entity, marking the end of a chapter that traced its roots from AppNexus through AT&T and ultimately into Microsoft.