Most traded currencies by value Currency distribution of global foreign exchange market turnover^[3]

Rank	Currency	ISO 4217 code (Symbol)	% daily share (April 2010)
1	United States dollar	USD ($)	84.9%
2	Euro	EUR (€)	39.1%
3	Japanese yen	JPY (¥)	19.0%
4	Pound sterling	GBP (£)	12.9%
5	Australian dollar	AUD ($)	7.6%
6	Swiss franc	CHF (Fr)	6.4%
7	Canadian dollar	CAD ($)	5.3%
8	Hong Kong dollar	HKD ($)	2.4%
9	Swedish krona	SEK (kr)	2.2%
10	New Zealand dollar	NZD ($)	1.6%
11	South Korean won	KRW (₩)	1.5%
12	Singapore dollar	SGD ($)	1.4%
13	Norwegian krone	NOK (kr)	1.3%
14	Mexican peso	MXN ($)	1.3%
15	Indian rupee	INR ()	0.9%
Other			12.2%
Total[15]			200%

There is no unified or centrally cleared market for the majority of FX trades, and there is very little cross-border regulation. Due to the over-the-counter (OTC) nature of currency markets, there are rather a number of interconnected marketplaces, where different currencies instruments are traded. This implies that there is not a single exchange rate but rather a number of different rates (prices), depending on what bank or market maker is trading, and where it is. In practice the rates are often very close, otherwise they could be exploited by arbitrageurs instantaneously. Due to London's dominance in the market, a particular currency's quoted price is usually the London market price. A joint venture of the Chicago Mercantile Exchange and Reuters, called Fxmarketspace opened in 2007 and aspired but failed to the role of a central market clearing mechanism.^{[citation needed]}
The main trading center is London, but New York, Tokyo, Hong Kong and Singapore are all important centers as well. Banks throughout the world participate. Currency trading happens continuously throughout the day; as the Asian trading session ends, the European session begins, followed by the North American session and then back to the Asian session, excluding weekends.