- Brian Morrissey

Online ad exchange platform AppNexus has added an extra $5 million in funding to help the company build out its product.
 
The funding is an "up-round" investment, added to an $8 million Series B round from September 2008. Existing investor Kodiak Venture Partners led the round, which included Venrock and First Round Capital. The company has raised more than $15 million.
 
The New York-based startup is among several players that aim to help ad buyers interact with the growing clout of ad exchanges. Executives who helped build two of the largest of such exchanges -- the Right Media platform used by Yahoo and the DoubleClick Ad Exchange owned by Google -- lead AppNexus.
 
"Over the next year, enormous quantities of display inventory are going to be open to real-time bidding and the auction model," said Michael Rubenstein, president of AppNexus, who joined the company in September after leading the DoubleClick Ad Exchange.
 
Companies like AppNexus, Invite Media and DataXu are building out technology platforms that will help advertisers, agencies and ad networks interact directly with exchanges, which allow buyers to select only the impressions that fit their audience criteria.
 
The move to exchanges and audience aggregators could represent a sea change for the industry since a majority of display ad inventory goes unsold. The ad exchanges promise advertisers the ability to target their ads directly to an audience rather than relying on content as a proxy. The goal is to make the buying and selling of display ads as efficient, automated and targeted as search ad auction systems.
 
"I had a unique vantage point," Rubenstein said. "I saw every company parade through. I think there's definitely a gap in the market to help on-ramp advertisers into this new world of ad exchanges and auction-based display."
 
Rubenstein allows that the current vogue for "people, not pages" alarms some publishers. It is particularly worrisome for mid-tier publishers without a strong brand to demand premium pricing that also lack a low-cost mass audience.
 
"It's redefining what's premium to them," Rubenstein said of advertisers "enamored by the audience-based model."