Foreign exchange is traded in an over-the-counter market where brokers/dealers negotiate directly with one another, so there is no central exchange or clearing house . The biggest geographic trading center is the United Kingdom, primarily London. According to TheCityUK , it is estimated that London increased its share of global turnover in traditional transactions from % in April 2007 to % in April 2010. Due to London's dominance in the market, a particular currency's quoted price is usually the London market price. For instance, when the International Monetary Fund calculates the value of its special drawing rights every day, they use the London market prices at noon that day.