Historically, Istanbul has been the center of the country's economic life because of its location as an international junction of land and sea trade routes. In 2005 the City of Istanbul had a GDP of $133 billion. In 2005 companies based in Istanbul made exports worth $41,397,000,000 and imports worth $69,883,000,000; which corresponded to 56.6% and 60.2% of Turkey's exports and imports, respectively, in that year. According to Forbes magazine, Istanbul had a total of 35 billionaires as of March 2008 (up from 25 in 2007), ranking 4th in the world behind Moscow (74 billionaires), New York City (71 billionaires) and London (36 billionaires), while ranking above Hong Kong (30 billionaires), Los Angeles (24 billionaires), Mumbai (20 billionaires), San Francisco (19 billionaires), Dallas (15 billionaires) and Tokyo (15 billionaires).
Istanbul has always been the financial capital of Turkey and the opening of specific markets in the city during the 1980s further strengthened this status. Inaugurated at the beginning of 1986, the Istanbul Stock Exchange (ISE) is the sole securities market of Turkey, established to provide trading in equities, right coupons, Government bonds, Treasury bills, revenue sharing certificates, bonds issued by the Privatization Administration and corporate bonds, and to carry out overnight transactions. In 1993 the ISE decided on gold market liberalization, and in 1995 the Istanbul Gold Exchange was established, which ended the gold bullion imports monopoly of the Turkish Central Bank and transferred it to the private sector members of the gold exchange.
Istanbul is also Turkey's largest industrial center. It employs approximately 20% of Turkey's industrial labor and contributes 38% of Turkey's industrial workspace. In addition, the city generates 55% of Turkey's trade and 45% of the country's wholesale trade, and generates 21.2% of Turkey's gross national product. Istanbul contributes 40% of all taxes collected in Turkey and produces 27.5% of Turkey's national product. Istanbul and its surrounding province produce cotton, fruit, olive oil, silk, and tobacco. Food processing, textile production, oil products, rubber, metal ware, leather, chemicals, pharmaceuticals, electronics, glass, machinery, automotive, transport vehicles, paper and paper products, and alcoholic drinks are among the city's major industrial products.
Istanbul is one of the most important tourism spots of Turkey. There are thousands of hotels and other tourist oriented industries in the city, catering to both vacationers and visiting professionals. In 2006 a total of 23,148,669 tourists visited Turkey, most of whom entered the country through the airports and seaports of Istanbul and Antalya. The total number of tourists who entered Turkey through Atatürk International Airport and Sabiha Gökçen International Airport in Istanbul reached 5,346,658, rising from 4,849,353 in 2005. Istanbul is also one of the world's major conference destinations and is an increasingly popular choice for the world's leading international associations