WPP plc, (Wire and Plastic Products) is a British multinational advertising and public relations company with its main management office in London, England, and its executive office in Dublin, Ireland. It is the world's largest advertising company by revenues, and employs around 190,000 people in 3,000 offices across 112 countries. It owns a number of advertising, public relations and market research networks, including IMRB, Millward Brown, Grey, Burson-Marsteller, Hill & Knowlton, JWT, Ogilvy & Mather, TNS, Young & Rubicam and Cohn & Wolfe. It is now one of the "Big Four" agency companies, alongside Publicis, Interpublic Group of Companies and Omnicom. 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.