AppNexus (APNX) Advertising Platform

AppNexus, often referred to by its former stock ticker-style shorthand APNX, is a pioneering cloud-based software platform that optimizes programmatic online advertising. Founded in 2007 by Brian O'Kelley and Mike Nolet in New York City, the company became a cornerstone of the ad-tech industry by providing a real-time bidding exchange and a suite of tools for both buyers and sellers of digital media.

In 2018, the branding underwent a significant shift when the company was acquired by the telecommunications giant AT&T. It was subsequently integrated into a new advertising unit called Xandr. The platform's ownership changed hands again in late 2021 when Microsoft reached an agreement to acquire Xandr, completing the deal in 2022. Today, the technology originally developed under the AppNexus name is a core component of Microsoft's global advertising ecosystem, supporting digital ad operations across various Microsoft properties and third-party partners.