Sylvester Stallone is partnering with STX Entertainment on a new film, the “Rocky” star told a crowd of theater owners at CinemaCon on Tuesday.

He was tightlipped about what the film would be about and wouldn’t even disclose the title. But Stallone heaped praise on the new studio and its business plan of making mid-budget films, which studios have largely abandoned in favor of launching major tentpoles and franchises.

“There is a happy medium,” said Stallone, noting that his biggest hits — movies such as “Rocky” and “Rambo” — would have fit in with that model.

He promised that the film will have “entertainment and commercial value.”

Barely a year old, STX Entertainment is making its first presentation at CinemaCon, the annual exhibition trade show unfolding this week in Las Vegas. The company showed footage from the Civil War drama “Free State of Jones,” bringing star Matthew McConaughey to the stage, where he drawled his signature “all right, all right, all right” line.

STX boasts financial backing from venture-capital firm and co-founder TPG, Chinese private-equity firm Hony Capital, and investors Gigi Pritzker and Beau Wrigley, along with film financing from China’s Huayi Brothers. It intends to spend as much as $1.1 billion annually on producing, marketing and self-distributing its films.

Calling the company “heavily capitalized,” STX president Sophie Watts kicked off the presentation by saying the studio was “poised to grow and built to last.”