REIT is an investment tool that owns and operates rent-yielding real estate assets. : Global investment company Blackstone and realty firm Embassy Group Monday filed its offer document with markets regulator Sebi to launch the country's first real estate investment trust (REIT) to raise over Rs 50 billion. Embassy Office Parks, the joint venture firm of Blackstone and Embassy, has filed the draft red herring prospectus (DRHP) with the regulator to launch REIT, which would be Asia's largest in terms of portfolio size of 33 million sq ft, sources said.