Apart from being the largest city and former political capital of the country, Istanbul has always been the centre of Turkey's economic life because of its location as a junction of international land and sea trade routes. Istanbul is also Turkey's largest industrial centre. It employs approximately 20% of Turkey's industrial labour and contributes 38% of Turkey's industrial workspace. 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. According to Forbes magazine, Istanbul had a total of 35 billionaires as of March 2008, ranking fourth in the world.
Originally established as the Ottoman Stock Exchange (Dersaadet Tahvilat Borsasi) in 1866, and reorganised to its current structure at the beginning of 1986, the Istanbul Stock Exchange (ISE) is the sole securities market of Turkey. During the 19th century and early 20th century, Bankalar Caddesi (Banks Street) in Galata was the financial centre of the Ottoman Empire, where the headquarters of the Ottoman Central Bank and the Ottoman Stock Exchange (1866) were located. Bankalar Caddesi continued to be Istanbul's main financial district until the 1990s, when most Turkish banks began moving their headquarters to the modern central business districts of Levent and Maslak. In 1995, the Istanbul Stock Exchange moved to its current building in the Istinye quarter.
Today, 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. 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.
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.