AppNexus completes Open AdStream® acquisition and closes $110 Million funding round

Press Release

New York – AppNexus, the world’s largest independent ad tech company, today announced the completion of its acquisition of Open AdStream® (OAS), a premium ad-serving technology. On September 22, 2014, the company announced that it would acquire OAS®, formerly known as Xaxis For Publishers, in a strategic transaction with WPP and Xaxis.

WPP also invested $25 million in AppNexus as part of a funding round led by a large, Boston-based public equity and asset management firm, totaling $110 million and which is now complete.

OAS® is one of the industry’s most trusted and effective platforms, having served prominent publishers around the world for more than 10 years. With the acquisition of OAS®, AppNexus has further cemented its position as a growing global technology leader dedicated to providing its clients with the most comprehensive solutions and powerful marketplaces in the industry. By combining AppNexus’ existing capabilities with the OAS® premium ad-serving technology, the company can offer a more complete technology stack to publishers that is independent from any media business and provides the latest innovations in a rapidly changing industry.

“We couldn’t have been more thrilled to welcome OAS to our world-class team at AppNexus, and to begin working together to build the most innovative publisher stack available,” said Brian O’Kelley, CEO and Co-founder, AppNexus. “From the very beginning, AppNexus has been revolutionizing the ad tech space, and we’ll continue to do so, providing all of our customers – including top programmatic media companies, agencies, advertisers, as well as publishers – with the best technology available to grow their businesses, and an independent platform that they can trust.”

One of New York’s most successful and highly-valued technology companies, AppNexus eclipsed $1 billion in total ad spend across its platform in 2013, and expects that figure to more than double in 2014, exceeding $2 billion. With the integration of OAS®, the company now has 800 employees across 20 global offices.

Specific terms of AppNexus’ acquisition of OAS® were not disclosed.


AppNexus is a technology company that provides trading solutions and powers marketplaces for Internet advertising. Its open, unified, and powerful programmatic platform empowers customers to more effectively buy and sell media, allowing them to innovate, differentiate, and transform their businesses. As the world’s largest independent ad tech company, AppNexus is led by the pioneers of the web’s original ad exchanges. Headquartered in New York City with ten global offices, AppNexus employs hundreds of the brightest minds in advertising and technology who believe that advertising powers the Internet. For more information, follow us at @AppNexus or visit us at