Mutual Broadcasting System

The Mutual Broadcasting System (commonly referred to simply as Mutual; sometimes referred to as MBS, Mutual Radio or the Mutual Radio Network) was an American commercial radio network in operation from 1934 to 1999. In the golden age of U.S. radio drama, Mutual 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.

Source: Wikipedia — Mutual Broadcasting System (CC BY-SA 4.0)