AppNexus Expands Real-time Bidding Globally With new Data Center in the Netherlands

NEW YORK, September 30, 2010 - AppNexus, the real-time ad platform, today announced that it has opened
its first data center outside North America — in Amsterdam, the Netherlands
– a move which significantly expands the opportunity for real-time bidding
(RTB) in Europe and the Middle East in response to rising demand among global
ad networks, demand-side platforms (DSPs) and other online advertising
companies in those regions.

AppNexus' state-of-the-art platform provides clients with unified access
across all major RTB ad exchanges including Google's DoubleClick Ad Exchange
and Microsoft's AdECN, as well as a cloud infrastructure scalable to tens of
billions of ad impressions a day. AppNexus has already established itself in
the international market, working with customers such as Infectious Media in
the United Kingdom, BannerConnect in the Netherlands and mexad in Germany.

"RTB has gained significant traction in the United States which has
earned the attention of sophisticated online advertising companies around the
world," said Brian O'Kelley, CEO of AppNexus. "Proximity to the ad servers of
the major European publishers and ad inventory sources, however, is critical
when the ads need to be served in real-time. With our new data center in
Amsterdam, we're excited to bring more robust RTB capabilities to ad
networks, DSPs and other clients in the European market. Our partners are
seeing incredible results in the US, and now this trend will be a global
game-changer for online advertising."

According to proprietary AppNexus server data, real-time bidding
impression volume in Europe and the Middle East is up to billions per day.
The United Kingdom is second in the world in RTB volume, after the United
States.

"Real-time bidding is central to the data-driven display trading services
that Infectious Media provides. AppNexus is a trusted provider of core RTB
technologies and infrastructure on which our Impression Desk biddable display
platform continues to develop," said Andy Cocker, Co-Founder and Managing
Partner, Infectious Media. "AppNexus' European server co-location turbo
charges our bidding capabilities and gives our clients a competitive edge in
the real-time marketplaces."

Steven Filler, Managing Director, Collective UK said, "The UK market
leads Europe in real-time bidding volume, and Collective UK plans to offer
our clients the best technology to harness this incredible opportunity.
Collective has a great track record leveraging the AppNexus platform for
real-time bidding in the United States, with incredible results for clients,
so we can definitely foresee working with them in the immediate future in the
UK."

AppNexus' data center in Amsterdam, co-located in a world-class facility
at the Equinix AM1 IBX, offers multiple currency and time zone capabilities,
and 24-hour support with transit latencies well under 10 milliseconds to much
of Europe.

ABOUT APPNEXUS

AppNexus is the real-time ad platform for ad networks, demand-side
platforms (DSPs) and other leading online advertising companies. Founded and
managed by the pioneers of the Web's original and most successful ad
exchanges at Yahoo!'s Right Media and Google's DoubleClick, AppNexus offers a
comprehensive suite of core infrastructure and ad technology capabilities
including data management, optimization, APIs, financial clearing and support
for directly negotiated media campaigns. Overall, AppNexus empowers
sophisticated companies to build, manage and optimize their entire display
advertising businesses and provides single-point integration to the largest
sources of inventory, including the major aggregators and exchanges like
Google's DoubleClick and Microsoft's AdECN.

Based in New York City, AppNexus is backed by an outstanding group of
investors, including Marc Andreessen and Ben Horowitz from LoudCloud/OpsWare;
First Round Capital; Venrock; Grape Arbor; Kodiak Venture Partners; Ron
Conway; and Khosla Ventures. For more information, go to
www.appnexus.com.

AppNexus Media Contacts: In the UK: David Tutin, +44(0)1672-861659, david at freelance-pr.co.uk; In the United States: Jenny Mulholland, +1-732-245-0021 (EST), jmulholland at appnexus.com; Andrea Roesch, +1-650-644-1700 (PST), aroesch at appnexus.com