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Interest rate parity
Interest rate parity (IRP) states that an appreciation or depreciation of one currency against another currency might be neutralized by a change in the interest rate differential. If US interest rates exceed Japanese interest rates then the US dollar should depreciate against the Japanese yen by an amount that prevents arbitrage. The future exchange rate is reflected into the forward exchange rate stated today. In our example, the forward exchange rate of the dollar is said to be at a discount because it buys fewer Japanese yen in the forward rate than it does in the spot rate. The yen is said to be at a premium.IRP showed no proof of working after 1990s. Contrary to the theory, currencies with high interest rates characteristically appreciated rather than depreciated on the reward of the containment of inflation and a higher yielding currency.Balance of payments model
This model holds that a foreign exchange rate must be at its equilibrium level - the rate which produces a stable current account balance. A nation with a trade deficit will experience reduction in its foreign exchange reserves which ultimately lowers (depreciates) the value of its currency. The cheaper currency renders the nation's goods (exports) more affordable in the global market place while making imports more expensive. After an intermediate period, imports are forced down and exports rise, thus stabilizing the trade balance and the currency towards equilibrium.Like PPP, the balance of payments model focuses largely on tradable goods and services, ignoring the increasing role of global capital flows. In other words, money is not only chasing goods and services, but to a larger extent, financial assets such as stocks and bonds. Their flows go into the capital account item of the balance of payments, thus, balancing the deficit in the current account. The increase in capital flows has given rise to the asset market model.
Nominal and real exchange rates
* The nominal exchange rate e is the price in domestic currency of one unit of a foreign currency. * The real exchange rate (RER) is defined as RER = e (\frac{P^*}{P} ), where P is the domestic price level and P * the foreign price level. P and P * must have the same arbitrary value in some chosen base year. Hence in the base year, RER = e.The RER is only a theoretical ideal. In practice, there are many foreign currencies and price level values to take into consideration. Correspondingly, the model calculations become increasingly more complex. Furthermore, the model is based on purchasing power parity (PPP), which implies a constant RER. The empirical determination of a constant RER value could never be realised, due to limitations on data collection. PPP would imply that the RER is the rate at which an organization can trade goods and services of one economy (e.g. country) for those of another. For example, if the price of a good increases 10% in the UK, and the Japanese currency simultaneously appreciates 10% against the UK currency, then the price of the good remains constant for someone in Japan. The people in the UK, however, would still have to deal with the 10% increase in domestic prices. It is also worth mentioning that government-enacted tariffs can affect the actual rate of exchange, helping to reduce price pressures. PPP appears to hold only in the long term (3–5 years) when prices eventually correct towards parity.More recent approaches in modelling the RER employ a set of macroeconomic variables, such as relative productivity and the real interest rate differential. N R_i = (R R_i + 1)(Expected \ inflation + 1) - 1
Exchange rate
In finance, the exchange rate (also known as the foreign-exchange rate, forex rate or FX rate) between two currencies specifies how much one currency is worth in terms of the other. For example an exchange rate of 123 Japanese yen (JPY, ¥) to the United States dollar (USD, $) means that JPY 123 is worth the same as USD 1. The foreign exchange market is one of the largest markets in the world. By some estimates, about 2 trillion USD worth of currency changes hands every day.The spot exchange rate refers to the current exchange rate. The forward exchange rate refers to an exchange rate that is quoted and traded today but for delivery and payment on a specific future date.
Quotations
An exchange rate quotation is given by stating the number of units of a price currency that can be bought in terms of 1 unit currency (also called base currency). For example, in a quotation that says the EUR/USD exchange rate is 1.3 (USD per EUR), the price currency is USD and the unit currency is EUR.Quotes using a country's home currency as the price currency (e.g., 0.50593 = $1 in the UK) are known as direct quotation or price quotation (from that country's perspective) ([1]) and are used by most countries.Quotes using a country's home currency as the unit currency (e.g., $1.97656 = £1 in the UK) are known as indirect quotation or quantity quotation and are used in British newspapers and are also common in Australia, New Zealand and Canada. * direct quotation: 1 foreign currency unit = x home currency units * indirect quotation: 1 home currency unit = x foreign currency unitsNote that, using direct quotation, if the home currency is strengthening (i.e., appreciating, or becoming more valuable) then the exchange rate number decreases. Conversely if the foreign currency is strengthening, the exchange rate number increases and the home currency is depreciating.When looking at a currency pair such as EUR/USD, many times the first component (EUR in this case) will be called the base currency. The second is called the counter currency. For example : EUR/USD = 1.33866, means EUR is the base and USD the counter, so 1 EUR = 1.33866 USD.Currency pair are given with four decimal places, except JPY with two decimal places (EUR/USD : 1.3386 - EUR/JPY : 165.29). In other words, quotes are given with 5 digits. Where rates are below 1, quotes frequently include 5 decimal places.
Valuing FX options: The Garman-Kohlhagen model
As in the Black-Scholes model for stock options and the Black model for certain interest rate options, the value of an european option on a FX rate is typically calculated by assuming that the rate follows a log-normal process.Examples
Suppose a United Kingdom manufacturing firm is expecting to be paid US$100,000 for a piece of engineering equipment to be delivered in 90 days. If the GBP strengthen against the US$ over the next 90 days the UK firm will lose money, as it will receive less GBP when the US$100,000 is converted into GBP. However, if the GBP weaken against the US$,then the UK firm will gain additional money. In this case, to protect the GBP value that the firm will receive in 90 day's time, the UK firm can purchase a GBP call/ USD put option (the right to sell part or all of their expected income for pounds sterling at a given rate near today's rate) to mitigate their risk of exchange rate fluctuation over the 90 days. Conversely another party may wish to have the reverse option for a similar reason. A market maker will buy and sell these options with the aim of making a profit while not incurring too much risk.The advantage of using an option instead is that it gives unlimited profit potential to the buyer at a limited cost (this cost is known as option premium).In 1983 Garman and Kohlhagen extended the Black-Scholes model to cope with the presence of two interest rates (one for each currency). Suppose that rd is the risk-free interest rate to expiry of the domestic currency and rf is the foreign currency risk-free interest rate (where domestic currency is the currency in which we obtain the value of the option; the formula also requires that FX rates - both strike and current spot be quoted in terms of "units of domestic currency per unit of foreign currency"). Then the domestic currency value of a call option into the foreign currency is c = S\exp(-r_f T)\N(d_1) - K\exp(-r_d T)\N(d_2)The value of a put option has value p = K\exp(-r_d T)\N(-d_2) - S\exp(-r_f T)\N(-d_1)where : d_1 = \frac{\ln(S/K) + (r_d - r_f + \sigma^2/2)T}{\sigma\sqrt{T}} d_2 = d_1 - \sigma\sqrt{T} S is the current spot rate K is the strike rate N is the cumulative normal distribution function rd is domestic risk free rate rf is foreign risk free rate and σ is the volatility of the FX rate.
Foreign exchange option
In finance, a foreign exchange option (commonly shortened to just FX option or currency option) is a derivative financial instrument where the owner has the right but not the obligation to exchange money denominated in one currency into another currency at a pre-agreed exchange rate on a specified date. The FX options market is the deepest, largest and most liquid market for options of any kind in the world. Most of the FX option volume is traded OTC but a fraction is traded on exchanges like the Philadelphia Stock Exchange, or the Chicago Mercantile Exchange for options on futures contracts.
For example a GBPUSD FX option might be specified by a contract allowing the owner to sell £1,000,000 and buy $2,000,000 on December 31. In this case the pre-agreed exchange rate, or strike price, is 2.0000 GBPUSD or 0.5000 USDGBP and the notional is £1,000,000. This type of contract is both a call on dollars and a put on sterling, and is often called a GBPUSD put by market participants. If the dollar is stronger than 2.0000 GBPUSD come December 31 (say at 1.9000 GBPUSD) then the option will be exercised, allowing the owner to sell GBP at 2.0000 and immediately buy it back in the spot market at 1.9000, making a profit of (2.0000 - 1.9000)*1,000,000 GBP = 100,000 USD in the process. If he immediately exchanges his profit, this amounts to 100,000/1.9000 = 52,631.58 GBP.
Retail Forex Trading
Take two of the most common currency pairs, the EUR/USD (the price for Euros in US dollars) and the GBP/USD (the price for The Great British Pound in US dollars). If there is positive economic news in the Euro zone and negative economic news in the United Kingdom, it is very conceivable that the EUR/USD would go up in value, meaning it is now more expensive in US dollars to purchase one EUR, and that the GBP/USD would go down in value, meaning it is now cheaper to buy Great British Pounds with US dollars. In this scenario, the US dollar went up in value against one currency and down in relation to another. It is important to understand this idea that currency pairs move mostly independently from one another. Currency pairs with similar currencies on one side (like the USD in the previous example) can be similarly affected by news regarding the common currency, but the crucial concept is that they don’t have to be.
United States dollar and the euro
Since the mid-20th century, the de facto world currency has been the United States dollar. According to Robert Gilpin in Global Political Economy: Understanding the International Economic Order (2001): "Somewhere between 40 and 60 percent of international financial transactions are denominated in dollars. For decades the dollar has also been the world's principle reserve currency; in 1996, the dollar accounted for approximately two-thirds of the world's foreign exchange reserves" (255).Many of the world's currencies are pegged against the dollar. Some countries, such as Ecuador, El Salvador, and Panama, have gone even further and eliminated their own currency in favor of the United States dollar. Since 1999, the dollar's dominance has begun to be undermined by the euro, that represents an equivalent size economy, with the prospect of more countries adopting the euro as their national currency. Quite a few of the world's currencies are pegged against the euro. They are usually Eastern European currencies like the Estonian kroon and the Bulgarian lev, plus several north African currencies like the Cape Verdean escudo and the CFA franc.
As of December 2006, the euro surpassed the dollar in the combined value of cash in circulation. The value of euro notes in circulation has risen to more than €610 billion, equivalent to US$800 billion at the exchange rates at this time.
