Nexstar Media Group Inc. is already attracting interest from private equity firms and rival media companies for a group of television stations that it’s promised to sell as part of its acquisition of Tribune Media Co., according to people familiar with the matter.

Cerberus Capital Management and Apollo Global Management LLC, as well as regional broadcasters EW Scripps Co., Gray Television Inc., Meredith Corp. and Tegna Inc., are circling the stations, which could fetch as much as $1 billion, said...