Visa has begun a review to consolidate its global buying account. Visa spent 417.8 million in marketing in the U.S., according to Ad Age’s Leading National Advertisers report. Visa has tapped EMM Group, London, an enterprise-marketing management firm, to oversee the review. Incumbent holding companies invited to participate in the pitch include Publicis Groupe, Omnicom Group, WPP Group and Aegis. The review does not include creative.