The media of New York City are internationally influential, and include some of the most important newspapers, largest publishing houses, most prolific television studios, and biggest record companies in the world. It is a major global center for the television, music, newspaper, book and magazine publishing industries. New York is also the largest media market in North America (followed by Los Angeles, Chicago, and Toronto). Some of the city's media conglomerates include Time Warner, the News Corporation, the Hearst Corporation, and Viacom. Seven of the world's top eight global advertising agency networks are headquartered in New York. Three of the "Big Four" record labels are also based in the city, as well as in Los Angeles. One-third of all American independent films are produced in New York.