WPP plc owns a number of advertising, public relations, media and market research networks, including Ogilvy, J. Walter Thompson, Young & Rubicam, Grey, IMRB, Millward Brown, Burson-Marsteller, Hill & Knowlton, TNS, GroupM, Kantar, and Cohn & Wolfe.[3] It is one of the "Big Five" agency companies, alongside Dentsu, Publicis, Interpublic Group of Companies and Omnicom.[5] WPP has a primary listing on the London Stock Exchange and is a constituent of the FTSE 100 Index. It has a secondary listing on NASDAQ.