New York--WPP Group plc, Omnicom Group Inc. and the Interpublic Group of Cos. Inc., the world's three biggest ad agencies, are to form an Internet exchange aimed at media buyers and sellers. It is the first time major ad agencies have announced plans to launch an exchange. In a statement, the companies said the as-yet-unnamed exchange, which will be a stand-alone company based in New York, will allow media buyers and sellers to exchange data. "Interpublic, Omnicom and WPP believe that technology presents a great opportunity to create a platform from which the billions of dollars now spent on media every week can be transacted much more effectively and cost efficiently," WPP Group CEO Martin Sorrell said in a statement. Other companies will be invited to join the exchange, whose CEO will be Michael Lotito. Previously, Lotito was president-COO of Initiative Media North America, Interpublic's media planning division.