In January 1995, The WB Television Network and the United Paramount Network (UPN) were launched,[1] each hoping to recreate the success of the Fox network, which had launched in October 1986 and became one of America's "major" networks through the successes of several early series (such as The Simpsons, Married... with Children, The X-Files, Melrose Place, Martin, In Living Color, COPS, Beverly Hills, 90210, and Fox Kids' airings of the Mighty Morphin Power Rangers) and its 1993 deal with the National Football League (NFL) to assume the broadcast rights to the National Football Conference (NFC) from CBS. Like with Fox at the time, The WB targeted a mostly teenage and young adult audience; UPN, however, aimed its programming at a broader demographic of adults between 18 and 49 years of age.

All three networks had been joint ventures between major Hollywood studios and large owners of previously independent stations – The WB was owned by the Warner Bros. Entertainment division of Time Warner, in a joint venture with the Tribune Company, and UPN was founded by Chris-Craft Industries, in a programming partnership with Paramount Pictures. In October 1993, Chris-Craft and the Paramount Stations Group reached affiliation agreements with most of the independents owned by the respective groups to serve as charter UPN affiliates.[2] That November, Tribune cut affiliation deals with The WB for all eight independents it owned at the time (including stations in New York City, Los Angeles and Chicago) – as well as a station in Boston that Tribune bought from the Gannett Company the following year, though only seven would join the network at launch due to the company's Atlanta station affiliating with CBS (its New Orleans station would follow suit in 1996, switching its affiliation to ABC);[3][4] Chris-Craft and Paramount also each owned independents in large and mid-sized markets (with the former owning stations in New York City and Los Angeles).

Both new networks launched to limited fanfare and generally poor results. Over the course of 11½ seasons, despite a number of minor-hit or cult-hit series such as Star Trek: Voyager, Star Trek: Enterprise, Charmed, 7th Heaven, Gilmore Girls, Girlfriends, Buffy the Vampire Slayer, Felicity, Moesha, Dawson's Creek, The Parkers, One on One, Roswell, and Kids' WB's airing of the anime Pokémon, neither network was able to attain the stature that Fox had gained in its first decade, much less that of the longstanding "Big Three" television networks (ABC, CBS and NBC). By early 2006, both networks were losing money, although The WB had been profitable a few seasons earlier; in slight contrast, UPN had never turned a profit and had already lost $800 million in its first five years of operation.[5] Reports indicated that the prospects for both networks were fading quickly.

A further complication was the various shifts in network and affiliate ownership at UPN. Shortly before its launch, Paramount Pictures' corporate parent Paramount Communications was purchased by Viacom, which later purchased a 50 percent stake in UPN in December 1996,[6][7] and acquired CBS in 2000. Viacom was permitted to keep interests in both networks, in effect, resulting in the Federal Communications Commission (FCC) lifting its long-standing ban on television station duopolies. Chris-Craft's relations with Viacom were strained in February 2000 when the latter firm exercised a contractual right to force Chris-Craft to either buy Viacom out of UPN, or sell its stake in the network to Viacom within a 45-day grace period. Chris-Craft subsequently filed a lawsuit against Viacom in the New York Supreme Court to block the CBS merger on grounds that a pact reached between Chris-Craft and Viacom in 1997 disallowed either company from owning "any interest, financial or otherwise" in "any competing network" through January 2001; however, New York Supreme Court judge Herman Cahn ruled against Chris-Craft's move for a permanent injunction motion in March 2000.[8][9][10] Chris-Craft could not find a suitable partner and sold its interest in UPN to Viacom for $5 million that April.[11][12][13] This had the adverse effect of making UPN one of the few networks not to have owned-and-operated flagship stations in New York City and Los Angeles.

Similarly, The WB had the distinction of being the only American broadcast network never to have had an O&O, as although minority owner Tribune operated its core charter stations, Time Warner held majority ownership in the network (with a maximum interest of 77.5 percent, during the final years of The WB's existence). Time Warner did acquire Atlanta independent WTBS (which served as the originating feed of then-superstation TBS) through its 1996 merger with the Turner Broadcasting System; however, WATL (which Tribune would acquire in 1999) served as the WB affiliate for that market throughout the network's run.

That August, when Chris-Craft put its television stations – most of them UPN affiliates – up for sale, it sold them to News Corporation's Fox Television Stations subsidiary instead of Viacom. At the time, Fox seemed to be a willing partner in UPN, but made no firm commitment.[14] On September 24, 2003, Fox Television Stations renewed affiliation agreements for its nine UPN stations for three years through 2006.[15] On December 31, 2005, Viacom split into two companies: a new company keeping the Viacom name (which took the original company's film and most of its cable television properties), and CBS Corporation (essentially the old Viacom renamed, which retained the broadcast properties, along with Showtime Networks). In this "split", ownership of UPN went to CBS Corporation.[16][17]

On January 24, 2006, CBS Corporation and Time Warner announced they would shut down both UPN and The WB that fall. In place of these two networks, a new "fifth" network that would be jointly owned by both companies, would launch, with a lineup made primarily of the most popular programs from both The WB and UPN. The network was given the name "The CW Television Network" ("CW" representing the first letters in "CBS" and "Warner Bros.").[18][19][20][21][22]

The CW immediately announced ten-year affiliation agreements with 16 WB affiliates owned by Tribune Broadcasting,[23] and 11 UPN owned-and-operated stations under CBS ownership, giving the new network coverage in all of the top 13 markets and a reach of 48 percent of the country. The remaining affiliates were to be drawn from the pool of stations affiliated with UPN and The WB. The CW took on The WB's base scheduling model (two hours of prime time programming each Monday through Friday and five hours on Sundays, a two-hour daytime block on weekdays and a five-hour Saturday morning children's block), which was larger in scope compared to UPN, which aired prime time programming only on weekdays and a two-hour repeat block on weekends at the time of the CW announcement.

It was immediately clear that most media markets which had stations that were owned by Tribune would receive the CW affiliation, leaving Fox Television Stations, UPN's second largest affiliate group (after the UPN O&Os owned by CBS Television Stations), without any network programming during primetime hours. Rumors began to circulate that Fox would develop its own network for those affected stations and others left out in the merger.[24] The rumors proved true, and on February 22, 2006, Fox announced the launch of its own network, MyNetworkTV, a programming service meant to fill the two nightly primetime hours that would open up on its UPN and WB-affiliated stations after the start of The CW. Fox also offered the service to other stations.[25][26]