INTEREST RATES AND EXCHANGE RATES
Nominal interest rates (i) in each country equal the required real rate of interest (r) and the expected rate of inflation over the period of time for which the funds are to be lent (I); that is, i = r+ I.
Economic theory tells us that interest rates reflect expectations about likely future inflation rates. In countries where inflation is expected to be high, interest rates also will be high, because investors want compensation for the decline in the value of their money. This relationship was first formalized by economist Irvin Fisher and is referred to as the Fisher effect. The Fisher effect states that a country’s “nominal” interest rate (i) is the sum of the required “real” rate of interest (r) and the expected rate of inflation over the period for which the funds are to be lent (I). More formally,
For example, if the real rate of interest in a country is 5 percent and annual inflation is expected to be 10 percent, the nominal interest rate will be 15 percent. As predicted by the Fisher effect, a strong relationship seems to exist between inflation rates and interest rates.15
We can take this one step further and consider how it applies in a world of many countries and unrestricted capital flows. When investors are free to transfer capital between countries, real interest rates will be the same in every country. If differences in real interest rates did emerge between countries, arbitrage would soon equalize them. For example, if the real interest rate in Japan was 10 percent and only 6 percent in the United States, it would pay investors to borrow money in the United States and invest it in Japan. The resulting increase in the demand for money in the United States would raise the real interest rate there, while the increase in the supply of foreign money in Japan would lower the real interest rate there. This would continue until the two sets of real interest rates were equalized.
It follows from the Fisher effect that if the real interest rate is the same worldwide, any difference in interest rates between countries reflects differing expectations about inflation rates. Thus, if the expected rate of inflation in the United States is greater than that in Japan, U.S. nominal interest rates will be greater than Japanese nominal interest rates.
International Fisher Effect
For any two countries, the spot exchange rate should change in an equal amount but in the opposite direction to the difference in nominal interest rates between countries.
Because we know from PPP theory that there is a link (in theory at least) between inflation and exchange rates, and because interest rates reflect expectations about inflation, it follows that there must also be a link between interest rates and exchange rates. This link is known as the international Fisher effect (IFE). The international Fisher effect states that for any two countries, the spot exchange rate should change in an equal amount but in the opposite direction to the difference in nominal interest rates between the two countries. Stated more formally, the change in the spot exchange rate between the United States and Japan, for example, can be modeled as follows:
where i$ and i¥ are the respective nominal interest rates in the United States and Japan, S1 is the spot exchange rate at the beginning of the period, and S2 is the spot exchange rate at the end of the period. If the U.S. nominal interest rate is higher than Japan’s, reflecting greater expected inflation rates, the value of the dollar against the yen should fall by that interest rate differential in the future. So if the interest rate in the United States is 10 percent and in Japan it is 6 percent, we would expect the value of the dollar to depreciate by 4 percent against the Japanese yen.
Do interest rate differentials help predict future currency movements? The evidence is mixed; as in the case of PPP theory, in the long run, there seems to be a relationship between interest rate differentials and subsequent changes in spot exchange rates. However, considerable short-run deviations occur. Like PPP, the international Fisher effect is not a good predictor of short-run changes in spot exchange rates.16
INVESTOR PSYCHOLOGY AND BANDWAGON EFFECTS
Empirical evidence suggests that neither PPP theory nor the international Fisher effect is particularly good at explaining short-term movements in exchange rates. One reason may be the impact of investor psychology on short-run exchange rate movements. Evidence reveals that various psychological factors play an important role in determining the expectations of market traders as to likely future exchange rates.17 In turn, expectations have a tendency to become self-fulfilling prophecies.
When traders move like a herd, all in the same direction and at the same time, in response to each others’ perceived actions.
A famous example of this mechanism occurred in September 1992 when the international financier George Soros made a huge bet against the British pound. Soros borrowed billions of pounds, using the assets of his investment funds as collateral, and immediately sold those pounds for German deutsche marks (this was before the advent of the euro). This technique, known as short selling, can earn the speculator enormous profits if he can subsequently buy back the pounds he sold at a much better exchange rate and then use those pounds, purchased cheaply, to repay his loan. By selling pounds and buying deutsche marks, Soros helped to start pushing down the value of the pound on the foreign exchange markets. More importantly, when Soros started shorting the British pound, many foreign exchange traders, knowing Soros’s reputation, jumped on the bandwagon and did likewise. This triggered a classic bandwagon effect with traders moving as a herd in the same direction at the same time. As the bandwagon effect gained momentum, with more traders selling British pounds and purchasing deutsche marks in expectation of a decline in the pound, their expectations became a self-fulfilling prophecy. Massive selling forced down the value of the pound against the deutsche mark. In other words, the pound declined in value not so much because of any major shift in macroeconomic fundamentals, but because investors followed a bet placed by a major speculator, George Soros.
George Soros, whose Quantum Fund has been very successful in managing hedge funds, has been criticized by world leaders because his actions can cause huge changes in currency markets.
According to a number of studies, investor psychology and bandwagon effects play an important role in determining short-run exchange rate movements.18 However, these effects can be hard to predict. Investor psychology can be influenced by political factors and by microeconomic events, such as the investment decisions of individual firms, many of which are only loosely linked to macroeconomic fundamentals, such as relative inflation rates. Also, bandwagon effects can be both triggered and exacerbated by the idiosyncratic behavior of politicians. Something like this seems to have occurred in Southeast Asia during 1997 when, one after another, the currencies of Thailand, Malaysia, South Korea, and Indonesia lost between 50 percent and 70 percent of their value against the U.S. dollar in a few months.
SUMMARY Of EXCHANGE RATE THEORIES
Relative monetary growth, relative inflation rates, and nominal interest rate differentials are all moderately good predictors of long-run changes in exchange rates. They are poor predictors of short-run changes in exchange rates, however, perhaps because of the impact of psychological factors, investor expectations, and bandwagon effects on short-term currency movements. This information is useful for an international business. Insofar as the long-term profitability of foreign investments, export opportunities, and the price competitiveness of foreign imports are all influenced by long-term movements in exchange rates, international businesses would be advised to pay attention to countries’ differing monetary growth, inflation, and interest rates. International businesses that engage in foreign exchange transactions on a day-to-day basis could benefit by knowing some predictors of short-term foreign exchange rate movements. Unfortunately, short-term exchange rate movements are difficult to predict.
• QUICK STUDY
1. What is the relationship between price inflation and exchange rates?
2. If the government of a nation expands the domestic money supply, other things being equal, what will be the impact on price inflation in that country?
3. What is the relationship between interest rates and exchange rates?
4. How might investor psychology influence exchange rates?
Exchange Rate Forecasting
LEARNING OBJECTIVE 5
Identify the merits of different approaches toward exchange rate forecasting.
A company’s need to predict future exchange rate variations raises the issue of whether it is worthwhile for the company to invest in exchange rate forecasting services to aid decision making. Two schools of thought address this issue. The efficient market school argues that forward exchange rates do the best possible job of forecasting future spot exchange rates, and, therefore, investing in forecasting services would be a waste of money. The other school of thought, the inefficient market school, argues that companies can improve the foreign exchange market’s estimate of future exchange rates (as contained in the forward rate) by investing in forecasting services. In other words, this school of thought does not believe the forward exchange rates are the best possible predictors of future spot exchange rates.