NebuAd was an American online advertising company based in Redwood City, California, with offices in New York and London and was funded by the investment companies Sierra Ventures and Menlo Ventures.
It was one of several companies which originally developed behavioral targeting advertising systems, and sought deals with ISPs to enable them to analyse customer's websurfing habits in order to provide them with more relevant, micro-targeted advertising. Phorm is a similar company operating out of Europe. Adzilla and Project Rialto also appear to be developing similar systems.
At one point, NebuAd had signed up more than 30 customers, mostly Internet access providers, its agreements with providers covered 10 percent of the broadband users in America. Due to fallout following public and Congressional concern, NebuAd's largest ISP customers pulled out. NebuAd closed for business in the UK in August 2008, followed by the US in May 2009. NebuAd UK Ltd was dissolved in February 2010.