Mutual started its baseball coverage in 1935, when the network joined NBC and CBS in national radio coverage. The three networks continued to share coverage of baseball's "jewels" (the All-Star Game and World Series) in this manner through 1938, with Mutual gaining exclusive rights to the World Series in 1939 and the All-Star Game in 1942. In 1949, CommissionerHappy Chandler negotiated a seven-year, $4,370,000 contract with the Gillette Safety Razor Company and the Mutual Broadcasting System for radio rights to the World Series, with the proceeds going directly into the pension fund. In 1957, NBC replaced Mutual as the exclusive national radio broadcaster for the World Series and All-Star Game.
Following the lead of the rival Liberty Broadcasting System, Mutual also aired regular-season Game of the Day broadcasts (a precursor to television's Game of the Week concept) to non-major-league cities throughout the 1940s and '50s.
In 1950, MBS acquired the television broadcast rights to the World Series and All-Star Game for the next six years. Mutual may have been reindulging in TV network dreams or simply taking advantage of a long-standing business relationship; in either case, the broadcast rights were sold to NBC in time for the following season's games at an enormous profit.