The Mutual Broadcasting System (MBS) was an American radio network, in operation from 1934 to 1999. Of the four national networks of American radio's classic era, Mutual had for decades the largest number of affiliates but the least certain financial position. In the golden age of U.S. radio drama, MBS was best known as the original network home of The Lone Ranger and The Adventures of Superman and as the long-time radio residence of The Shadow. For many years, it was the national broadcaster for baseball's All-Star Game and World Series and Notre Dame football. From the mid-1930s and for decades after, Mutual ran a highly respected news service accompanied by a variety of popular commentary shows. Toward the end of its run as a major programmer, it introduced the country to Larry King.
For the first eighteen years of its existence, MBS was owned and operated as a cooperative, setting the network apart from its competitors: Mutual's members shared their own original programming, transmission and promotion expenses, and advertising revenues. By late 1936, the Mutual Broadcasting System had affiliates from coast to coast. Its business structure would change after General Tire assumed majority ownership in 1952 through a series of regional and individual station acquisitions.
Once General Tire sold the network in 1957, Mutual's ownership was largely disconnected from the stations it served, leading to a more conventional, top-down model of program production and distribution. Not long after the sale, one of the network's new executive teams was charged with accepting money to use Mutual as a vehicle for foreign propaganda. The network was severely damaged, but soon rebounded. Mutual changed hands frequently in succeeding years—even leaving aside larger-scale acquisitions and mergers, its final direct corporate parent, Westwood One, which purchased it in 1985, was the seventh in a string of new owners that followed General Tire.