Mergers and acquisitions always have been a staple of the advertising agency business. Size matters for agency holding conglomerates such as the Interpublic Group of Companies Inc., Omnicom Group Inc., WPP Group PLC and Publicis Groupe. The more offerings under one roof, the better the chances of winning multimillion dollar accounts across a global footprint. And, of course, with MA activity may come culture clash, diffused focus and the opportunity to cut duplicated costs depending on how the deal is handled and its purpose.