In 1980, Green formed SL Green Properties, Inc. His strategy was to buy Class B office buildings, invest some money to redo their lobbies, facades and add other amenities and then raise the rents closer to Class A levels as older tenants moved out. This strategy was successful, and SL Green Realty Corp. went public in 1997, trading on the New York Stock Exchange under the stock ticker of SLG. The company was the first REIT to be focused solely on Manhattan office properties. SL Green Realty Corp. has investment interests in 77 Manhattan office buildings comprising nearly 40 million square feet of space.