Jack Sitt is a New York City-based real estate investor and member of the family that owns and runs Sitt Asset Management, which he founded with his brothers Ralph, David, and Eddie, and their mother Marilyn. He left the firm and sued it and his brother Ralph, alleging that he was deprived of millions of dollars in distributions and commission. He still maintains a 20 percent stake in Sitt Asset Management.

Sitt founded Jack Sitt Real Estate LLC in 2012, and in 2013, Sitt launched the online subletting platform Ditch the Space.