Television: Tribune Broadcasting Co. has invested $12 million to acquire a 12.5% stake in Time Warner Inc.'s new television network. The investment extends the role of Tribune, an independent group of eight TV stations that has agreed to carry WB Network programming on six of its stations. Under the original affiliate agreement, Tribune agreed to clear the shows for the rights to buy up to 25% of the WB, which had tiny ratings and one prime-time night of programming in its first season. Whereas Chris-Craft Industries, Viacom Inc.'s station-group partner in United Paramount Network, has agreed to shoulder the losses of that struggling new network for its first couple of years, Time Warner is bearing the losses for WB. Time Warner is expected to lose $70 million on it this year, and $300 million or more before it breaks even. Tribune has the right to exercise its option for another 12.5% stake in either January, 1997, or January, 1998.