It will premier in the Fall 2017.

In the Event “Fantasia Bunko Daikanshasai” it has been announced that a new anime based on Full Metal Panic! has been greenlit and it will have the name “Full Metal Panic! IV”. Alongside the announcement a teaser image and the staff has been shown.

Katsuichi Nakayama (Bodacious Space Pirates The Movie: Abyss of Hyperspace) it´s the director at studio XEBEC; Shoji Gatoh (Full Metal Panic!´s creator) is making the series composition and writting the scripts.

Besides that a Drama CD called “Dancing Very Christmas” is in the works.

Via: Anime News Network