Viebranz will report to AOL president and chief operating officer Ron Grant.
The heads of Advertising.com, Lynda Clarizio, and AOL brand solutions, Kathy Kayse, will report to Viebranz.
Platform A will reach more than 90% of the US online audience according to Comscore Media Metrix.
In addition, AOL said it is moving its corporate headquarters to New York City from Dulles, Virginia. It painted the moves as the final stage in its transition from an internet access business to an ad-funded content business.
Randy Falco, chairman and chief executive of AOL, said: "New York City is the centre of advertising, so it makes perfect sense to locate our corporate headquarters here."
Finally, AOL has signed an agreement with PC manufacturer HP to bundle its portal, toolbar and search engine with HP models sold in several countries around the world.