The FCC generally allows stations that share ownership to use the same callsign for TV, FM, and AM. Not always in the same area either; KCBS-AM is in San Francisco, while KCBS-FM and KCBS-TV are in Los Angeles. Additionally, stations are allowed to keep their call sign when ownership changes, so even though KCBS-FM and AM are no longer owned by the owners of KCBS-FM, they have chosen to keep the same call signs.