| Company type | Subsidiary | 
|---|---|
| Industry | Online advertising | 
| Founded | 2007 | 
| Headquarters | New York City, United States | 
| Area served | Worldwide | 
| Key people | Michael Rubenstein (president) | 
| Products | Infrastructure as a service Ad serving Analytics | 
| Number of employees | 1000+ | 
| Parent | Xandr (2018-present) | 
Xandr, formerly known as AppNexus, is an American multinational technology company operating a cloud-based software platform that enables and optimizes programmatic online advertising. [1] Headquartered in the Flatiron District of New York City, the company has 23 offices in North America, Latin America, Europe, Asia and Australia.[ citation needed ]
AppNexus offers online auction infrastructure and technology for data management, optimization, financial clearing and support for directly negotiated advertising campaigns. It has both demand-side platform (DSP), supply-side platform (SSP), and ad serving functionalities. It integrates with advertising sources including Google's "Authorized Buyers" ad exchange, Magnite, Pubmatic and other aggregators. [2] [3] It operates out of multiple data centers, including one in Amsterdam serving Europe and the Middle East, in a facility shared with Equinix. [4]
In June 2018, AT&T announced it was acquiring the company and putting it under its Xandr division as a subsidiary. [5] AppNexus was reportedly sold for $1.6 billion, while most news outlets speculated the company did not sell for less than $2 billion. [6]
In October 2019, Xandr purchased Clypd, a privately held technology company focused on enabling programmatic buying of linear television advertising. [7]
In December 2021, AT&T announced that they had agreed to sell Xandr to Microsoft for an undisclosed price, subject to customary closing conditions, including regulatory reviews. [8]
AppNexus was founded by former Right Media staff, CTO Brian O'Kelley, and Mike Nolet, product manager and director of analytics, [9] with Michael Rubenstein, a former vice president and general manager at Google DoubleClick, who joined AppNexus as president in September 2009. [10] The company was financially backed by Microsoft, Khosla Ventures, First Round Capital, Venrock, [11] Kodiak Venture Partners, Marc Andreessen, Ben Horowitz, and Ron Conway; as of 2015 the company had raised $250 million in financing. O'Kelley stepped down as CEO in October 2018. [12]