As KDKA radio had long been an affiliate of the NBC Blue Network (Westinghouse was a co-founder of RCA, NBC's then-parent company), it was expected that KDKA-TV would eventually become a primary affiliate of the NBC television network. But the network was seeking to purchase Westinghouse's Philadelphia stations, KYW radio and WPTZ (now KYW-TV). When Westinghouse balked, NBC threatened to pull its programming from WPTZ and Boston's WBZ-TV unless Westinghouse agreed to trade its Philadelphia properties for NBC's radio and television properties in Cleveland. (Related to the trade, Westinghouse received a cross-station waiver from the FCC to own the Cleveland properties due to overlapping signals with KDKA radio and channel 2.) The decision would lead to an acrimonious relationship between Westinghouse and NBC in later years. Two years after the ownership change, channel 2 became a primary affiliate of the higher-rated CBS network instead. KDKA-TV retained secondary affiliations with NBC until WIIC-TV (channel 11, now WPXI) signed on in 1957, and ABC until WTAE-TV (channel 4) signed on in 1958. Despite the ending of its commercial VHF monopoly, KDKA-TV did welcome competitor WIIC-TV on the air. KDKA-TV became the flagship station of Westinghouse's broadcasting arm, Group W. During the late 1950s, KDKA-TV was briefly affiliated with the NTA Film Network, sharing the affiliation with WTAE-TV, WIIC-TV, and WQED. On November 22, 1963, newscaster Bill Burns provided almost three hours of live coverage after the shooting of President John F. Kennedy.