SL Green Realty Corp an SP 500 company and Manhattans largest office landlord is a fully integrated real estate investment trust or REIT that is focused primarily on acquiring managing and maximizing value of Manhattan commercial properties As of December 31 2020 SL Green held interests in 88 buildings totaling 382 million square feet This included ownership interests in 286 million square feet of Manhattan buildings and 87 million square feet securing debt and preferred equity investments