Complex sentence: WLS had been owned and operated by the radio division of the American Broadcasting Company (ABC) since the purchase of its parent company in 1959 and the subsequent merging with WENR, a station with which WLS had shared its frequency since the 1920s.
Split into simpler sentences: WLS had been wholly owned and operated by the radio division of the American Broadcasting Company (ABC) since the purchase of its parent company in 1959. Five years earlier WLS was merged with WENR, a station with which WLS had shared its frequency since the 1920s.