London--TNS plc, parent company of CMR, said Wednesday that it has agreed to acquire Interpublic Group of Cos.' research arm, NFO WorldGroup, in a $425 million deal that would create one of the top three market information companies in the world. TNS said the acquisition would strengthen its ability to collect data online. Another advantage to the deal, the company said, would be a reduction in operating costs. "We believe that, by combining NFO with TNS, we will be able to generate significant cost and revenue synergies," said Tony Cowling, chairman of TNS, in a statement. Under the terms of the deal, $400 million would be paid in cash upon completion of the deal, and $25 million in stock would be issued to Interpublic upon completion.