A "City Mayors" survey ranked Dubai 44th among the world's best financial cities in 2007, while another report by "City Mayors" indicated that Dubai was the world's 27th richest city in 2012, in terms of purchasing power parity (PPP). Dubai is also an international financial centre (IFC) and has been ranked 37th within the top 50 global financial cities as surveyed by the MasterCard Worldwide Centres of Commerce Index (2007), and 1st within the Middle East. Since it opened in September 2004, the Dubai IFC has attracted, as a regional hub, leading international firms and set-up the NASDAQ Dubai which lists equity, derivatives, structured products, Islamic bonds (sukuk) and other bonds. The Dubai IFC model is an independent risk-based regulator with a legislative system consistent with English common law.