Incubic Venture capital led the round, which included additional existing investors Monitor Ventures and Walt Disney Co.-backed Steamboat Ventures.
Greystripe has raised a total of $15.6 million to date, last raising a second round of $8.9 million in May 2007 and a $1.2 million first round in October 2006. The company declined to discuss whether its latest round was at a higher or lower valuation.
The start-up has developed technology designed to allow advertising agencies to click on a mobile option to extend their existing online advertising campaigns beyond computer screens or TV. Greystripe aims to take flash advertisement and extend it beyond its online format to a mobile format. Flash advertisements have predominantly appeared online, rather than on mobile devices.
Michael Chang, Greystripe chief executive, said in a statement:
For too long the mobile advertising world has built a silo approach to their business.
Those days are over. It's time to join the online advertising world and bring new value in terms of reach, targeting and interactivity.
Among the smartphones that Greystripe works with, it delivers rich media flash ads on Apple's iPhone.