With an impressive list of innovative companies in its portfolio, including Facebook and Netflix, Technology Crossover Ventures is now rallying behind AppNexus in a $75 million Series D round of financing that brings the company's pre-money valuation to over $550 million. Based in New York City, AppNexus is the developer of a virtualized cloud computing platform for online advertising applications. While several companies have cropped up to offer similar services in the last few years, AppNexus has an all-star crew on deck, including CEO Brian O’Kelley, the former CTO of Right Media. The ad exchange platform was acquired by Yahoo! in 2007 to the tune of $850 million. Other big-name investors are on board for AppNexus’ Series D round, including Tribeca Venture Partners and Venrock.