The foreign currency exchange, or Forex, is the largest and most liquid market in the world. The market is open 24 hours a day, seven days a week, in New York, Hong Kong, and Tokyo. Because it is based on a fixed rate system, trades take place in milliseconds. Investors and companies benefit from the constant price fluctuations that can affect their investments. This information is used by banks and other financial institutions to make informed decisions about their trading and investing.