MasterCard Incorporated or MasterCard Worldwide is an American multinational financial services corporation headquartered in the MasterCard International Global Headquarters, Purchase, New York, United States, in Westchester County. The Global Operations Headquarters is located in O'Fallon, Missouri, United States, a suburb of St. Louis, Missouri. Throughout the world, its principal business is to process payments between the banks of merchants and the card issuing banks or credit unions of the purchasers who use the "MasterCard" brand debit and credit cards to make purchases. MasterCard Worldwide has been a publicly traded company since 2006. Prior to its initial public offering, MasterCard Worldwide was a cooperative owned by the more than 25,000 financial institutions that issue its branded cards.