The decentralized nature of the forex market enables traders to buy and sell currencies anytime during the day except on Saturdays and Sundays. This 24-hour service is made possible by financial centers located in various parts of the globe at different time zones. Furthermore, currency trading does not suspend even on holidays since special days vary from one country to another. Although the market is open all throughout the day and night without holidays, certain forex trading hours need to be observed. Experienced investors trade on the busiest part of the day when buying and selling transactions are highly active resulting to frequent fluctuations in currency values.

In determining the most desirable foreign exchange trading hours, traders choose a span of time when the busiest markets around the world are active. The London session, which commences from 8:00 GMT to 17:00 GMT, is the busiest financial center. Next in rank is the New York session that spans between 13:00 GMT and 22:00 GMT. Then, the Sydney session is the third busiest starting from 22:00 GMT to 7:00 GMT the following trading day. Finally, the Tokyo session is the fourth busiest beginning from 23:00 GMT until 9:00 GMT the next trading day.

Aside from considering the most active financial market individually, investors also consider the time of the day when market sessions overlap since these create an additive effect towards the overall busyness of the trading sessions. From the established trading schedules of the four busiest financial centers, the overlap of London and New York sessions is the most ideal timespan for trading. These two sessions overlap from 13:00 GMT to 17:00 GMT. Another overlap with the London session is observed with the Tokyo session beginning at 8:00 GMT and ending at 9:00 GMT. The third desirable overlap occurs between the Sydney and Tokyo sessions from 24:00 GMT to 7:00 GMT. Altogether, these overlaps are the most desirable trading periods.

Traders take note of the fact that profits are gained by capitalizing on the volatility of the market; hence, the more active the session is, the more desirable. In addition to determining the best forex trading hours, traders also observe the opening of every trading week. After the weekend rest, market action resumes when the financial center in Wellington, New Zealand opens. In every opening instance, traders take into consideration the events that took place during the weekend since it will significantly impact the first trading day of the week.