Hedge funds – Somewhere around 70 to 90% of all foreign exchange transactions are speculative in nature. This means, the person or institutions that bought or sold the currency has no plan of actually taking delivery of the currency; instead, the transaction was executed with sole intention of speculating on the price movement of that particular currency. Retail speculators (you and I) are small cheese compared to the big hedge funds that control and speculate with billions of dollars of equity each day in the currency markets.
The mere expectation or rumor of a central bank foreign exchange intervention might be enough to stabilize the currency. However, aggressive intervention might be used several times each year in countries with a dirty float currency regime. Central banks do not always achieve their objectives. The combined resources of the market can easily overwhelm any central bank.[62] Several scenarios of this nature were seen in the 1992–93 European Exchange Rate Mechanism collapse, and in more recent times in Asia.
The foreign exchange market (Forex, FX, or currency market) is a global decentralized or over-the-counter (OTC) market for the trading of currencies. This market determines foreign exchange rates for every currency. It includes all aspects of buying, selling and exchanging currencies at current or determined prices. In terms of trading volume, it is by far the largest market in the world, followed by the Credit market.[1]

The yellow boxes above highlight some examples of bullish harami long setups and bearish harami short setups. In this instance, the five setups occur over one trading day. Some days may have more, some days may have less. It is also noticeable that there are some winning setups, some losing setups and one that - if an order was placed for the setup - did not trigger the entry price.

National central banks play an important role in the foreign exchange markets. They try to control the money supply, inflation, and/or interest rates and often have official or unofficial target rates for their currencies. They can use their often substantial foreign exchange reserves to stabilize the market. Nevertheless, the effectiveness of central bank "stabilizing speculation" is doubtful because central banks do not go bankrupt if they make large losses as other traders would. There is also no convincing evidence that they actually make a profit from trading.
Forex brokers provide leverage up to 50:1 (more in some countries). For this example, assume the trader is using 30:1 leverage, as usually that is more than enough leverage for forex day traders. Since the trader has $5,000, and leverage is 30:1, the trader is able to take positions worth up to $150,000. Risk is still based on the original $5,000; this keeps the risk limited to a small portion of the deposited capital.
Governments / Central banks – A country’s central bank can play an important role in the foreign exchange markets. They can cause an increase or decrease in the value of their nation’s currency by trying to control money supply, inflation, and (or) interest rates. They can use their substantial foreign exchange reserves to try and stabilize the market.
More specifically, the spot market is where currencies are bought and sold according to the current price. That price, determined by supply and demand, is a reflection of many things, including current interest rates, economic performance, sentiment towards ongoing political situations (both locally and internationally), as well as the perception of the future performance of one currency against another. When a deal is finalized, this is known as a "spot deal". It is a bilateral transaction by which one party delivers an agreed-upon currency amount to the counter party and receives a specified amount of another currency at the agreed-upon exchange rate value. After a position is closed, the settlement is in cash. Although the spot market is commonly known as one that deals with transactions in the present (rather than the future), these trades actually take two days for settlement.