The Lightstone Group is a privately held real estate investment firm founded in 1988 by David Lichtenstein. The company's portfolio includes multifamily apartments, office buildings, hotels, shopping centers and industrial properties throughout the United States and Canada. The company has offices in New York City, New Jersey, Maryland, and Illinois. One of Lightstone's most profitable ventures began in 2002 with the acquisition of Prime Outlets, a Puerto Rico-based outlet mall. The investment firm grew the holding through add-on acquisitions until 2010, when it sold the entire Prime Outlets portfolio to Simon Property Group, netting a profit of $450 million. Its acquisition of Extended Stay Hotels was less successful. Lightstone was forced to give up control of the chain after it filed for bankruptcy in 2009. The company's divestments have included the 2015 sale of a portion of a Gowanus rental development to Atlantic Realty Development; acquisitions in New York include the June 2015 purchase of a residential rental building at 40 East End Avenue in Yorkville in a $32.5 million all-cash deal. As of 2015, Lightstone planned to demolish the six-story, 40-unit building on the site and replace it with an 18-story, 30-unit condominium.