On January 24, 2006, the Warner Bros. Entertainment unit of Time Warner (which operated The WB) and CBS Corporation (which acquired UPN through its split from Viacom in December 2005) announced that the two companies would respectively shut down UPN and The WB, and enter into a joint venture to form a new "fifth" broadcast television network, The CW, that would initially feature a mix of programming from both of its forerunner networks as well as new content developed specifically for The CW. WTTO, however, continued to show The WB's programming until The WB's "The Night of Favorites and Farewells," which aired on September 17, 2006. On May 2, 2006, Sinclair Broadcast Group announced that it had signed an affiliation agreement with the network, in which WTTO would become the Birmingham charter affiliate of The CW; when it officially joined the network upon its debut on September 18, WTTO/WDBB adopted "CW 21" as its official branding (although, the station sometimes identifies as "CW 21 Alabama" in some promotional imaging); sister station WABM affiliated with MyNetworkTV, a new secondary service started by Fox, on September 5, 2006.