Consider this: large volumes of forex are traded in the markets due to the necessity of currency exchange required in international trade. Large institutions may need to settle accounts in a cross-border manner quite frequently. As an example, an American company, looking to pay its German division, will need to pay them in euros. This means a forex transaction will be completed, and will likely influence the EUR/USD pair, even if only slightly.
The foreign exchange market is extremely active all day long with price quotes constantly changing. It is the only market that truly operates 24 hours a day and five days a week. Currencies are traded on the international interbank market in Zurich, Hong Kong, New York, Tokyo, Frankfurt, London, Sydney and Paris. This means that across almost every time zone the market is active - when the working day ends in one part of the world, in the other hemisphere, at that very moment, banks have already opened their doors and trading continues.
Money transfer companies/remittance companies perform high-volume low-value transfers generally by economic migrants back to their home country. In 2007, the Aite Group estimated that there were $369 billion of remittances (an increase of 8% on the previous year). The four largest foreign markets (India, China, Mexico, and the Philippines) receive $95 billion. The largest and best-known provider is Western Union with 345,000 agents globally, followed by UAE Exchange. Bureaux de change or currency transfer companies provide low-value foreign exchange services for travelers. These are typically located at airports and stations or at tourist locations and allow physical notes to be exchanged from one currency to another. They access foreign exchange markets via banks or non-bank foreign exchange companies.