Hollywood's involvement with radio predates the movies' ability to talk. From the earliest years of broadcasting, farsighted film producers and studio heads saw in radio a promotional medium made to order for enhancing the popular reach and appeal of their valuable entertainment empires. As sound film debuted and brought members of the "radio trust"—RCA and AT&T—into closer connection with film operations, several major studios made countermoves into the business of network radio. Though largely excluded from network ownership, the studios formed an alliance with the advertising agencies, which by the mid-1930s were producing the bulk of commercial programs on the air. "Prestige" radio production had moved to Hollywood by the late 1930s, and the lively process of mutual influence and exchange enriched both industries, setting the stage for Hollywood's increasing domination of television beginning in the late 1950s. Yet even as television took over the entertainment genres and cultural functions that had been created by network radio, the film industry, by expanding into other areas of media production and distribution, remained a player in the radio business. In the twenty-first century, all five major over-the-air television networks (NBC/Universal, CBS/Viacom/Paramount, ABC/Disney, Fox, and CW [formerly WB and UPN] as well as the majority of cable channels either bear a studio's name or are part of a filmmedia conglomerate. Producers, writers, directors, stars, and properties flow seamlessly from one medium to the other. This process began in radio.