Despite the influx of advertisers and their money – or perhaps because of them – the 1940s were not without bumps for the radio networks. The biggest challenge came in the form of the FCC's chain broadcasting investigation, often called the "monopoly probe".[72] Though it started in 1938, the investigation only gathered steam in 1940 under new-broom chairman James L. Fly.[73] By the time the smoke had cleared in 1943, NBC had already spun off its Blue Network, which became the American Broadcasting Company (ABC).