AOL's first attempt to buy a European ad company had failed earlier this year, when the shareholders of the Swedish firm TradeDoubler turned down an offer of $900 million.
The Adtech acquisition expands Advertising.com's global ad-serving network, with a focus on ad management, delivery and reporting applications. "Publishers will be able to better manage their own advertiser campaigns," said Lynda Clarizio, president of Advertising.com, "as well as better monetize their available inventory."
News of the deal came one day after AOL agreed to buy Third Screen Media--allowing Advertising.com to extend into mobile--and one year after its acquisition of audio and video ad company Lightningcast.
AOL's strategy of bolstering Advertising.com's services through acquisition reflects a wave of consolidation hitting the online ad market, led by Google's plan to buy DoubleClick for $3.1 billion.
Securing a controlling stake in Adtech allows Advertising.com to expand the volume of ads it delivers in Europe. Adtech, based in Frankfurt, serves Web publishers in 25 countries--with clients including Clear Channel Outdoor in Sweden and British Sky Broadcasting's Sky.com.
Adtech has also made inroads into the U.S. market. Last September, it opened its first U.S. office, and it recently signed A&E Television Networks and its network of sites, including AETV.com, History.com and Biography.com.
Advertising.com has been a major driver of growth for AOL. Analysts recently credited the ad network with helping to drive up AOL's first-quarter ad sales 40% in the first quarter on a year-to-year basis. And in April, Advertising.com won the privilege to provide display and video ad management services for the yet-unnamed video venture between NBC Universal and News Corp.