Despite John Shepard's affiliation of his Yankee Network stations with CBS, he still became involved in the founding of a new network, which came to be known as the Mutual Broadcasting System, and he served on its board of directors. Beginning around 1936, the Yankee Network also started to carry some Mutual programs. Meanwhile, there were some changes in Boston radio that affected the Yankee Network. CBS had begun purchasing stations, in addition to providing network programming. In early 1936, CBS purchased Boston's WEEI, making it necessary for Shepard's WNAC to affiliate with a different network, NBC's Red Network. The change officially took place in late September of that year.