It has been a miserable year for the holding companies that own the world’s largest advertising groups, with shares in WPP, Publicis, Omnicom and Interpublic Group all down sharply over the past 12 months. Consumer groups are rethinking their marketing spending while unease about the effectiveness of digital advertising has damped investor spirits. With advertising’s Mad Men in danger of becoming sad men, what future is there for the holding companies? Their business model, which has traditionally brought together creative agencies, media buying and planning groups, is under attack on multiple fronts.