Why Are Exchange Rates So Volatile?
The high volatility of foreign exchange rates surprises many people. Thirty or so years ago, economists generally believed that allowing exchange rates to be determined in the free market would not lead to large fluctuations in their values. Recent experience has proved them wrong. If we return to Figure 15.1, we see that exchange rates over the 1990–2010 period have been very volatile. The asset market approach to exchange rate determination that we have outlined in this chapter gives a straightforward explanation of volatile exchange rates. Because expected appreciation of the domestic currency affects the expected return on foreign deposits, expectations about the price level, inflation, trade barriers, productivity, import demand, export demand, and the money supply play important roles in determining the exchange rate. When expectations about any of these variables change, as they do—and often at that—our model indicates that there will be an immediate effect on the expected return on foreign deposits and therefore on the exchange rate. Because expectations on all these variables change with just about every bit of news that appears, it is not surprising that the exchange rate is volatile. Because earlier models of exchange rate behavior focused on goods markets rather than asset markets, they did not emphasize changing expectations as a source of exchange rate movements, and so these earlier models could not predict substantial fluctuations in exchange rates. The failure of earlier models to explain volatility is one reason why they are no longer so popular. The more modern approach developed here emphasizes that the foreign exchange market is like any other asset market in which expectations of the future matter. The foreign exchange market, like other asset markets such as the stock market, displays substantial price volatility, and foreign exchange rates are notoriously hard to forecast.