Realtime ad bidding network AppNexus today announced that it raised $50 million in a Series C financing. Investors include Microsoft, Venrock, Kodiak Venture Partners and First Round Capital. The round brings the total capital raised by AppNexus since its founding to $65.5 million. The company first raised an angel round in 2007 from Ron Conway, Marc Andreesen, Ben Horowitz, Khosla Ventures, and First Round Capital.
AppNexus is based in New York City, and was founded by Brian O’Kelley, who was also a co-founder of Right Media. (Yahoo purchased Right Media in 2007 for about $700 million).
AppNexus calls itself a realtime bidding platform for advertisers. It allows advertisers to bid for display ad spots across the Internet through 15 different ad networks. Advertisers can optimize for cost-per-clicks, cost-per-impressions, and other metrics.