"Trending Down" will star Hoffman (Death of a Salesman, Long Day's Journey Into Night) as a man whose life begins to crumble when his advertising agency is taken over. It is characterized as a "blistering attack on our youth-obsessed culture, and a darkly comic examination of what it means to matter. Or matter not."
Hoffman will play Thom Payne, with Kathryn Hahn expected to portray his wife.
Mitchell, who also directed his film of Hedwig, has directed "Short Bus" and "Rabbit Hole."
Shalom Auslander ("This American Life") created the series that was developed by Ken Kwapis.