Currency trading is a 24-hour market that is only closed from Friday evening to Sunday evening, but the 24-hour trading sessions are misleading. There are three sessions that include the European, Asian and United States trading sessions. Although there is some overlap in the sessions, the main currencies in each market are traded mostly during those market hours. This means that certain currency pairs will have more volume during certain sessions. Traders who stay with pairs based on the dollar will find the most volume in the U.S. trading session.