The modern monetary theories on short-term exchange rate volatility take into consideration the short-term capital markets' role and the long-term impact of the commodity markets on foreign exchange. These theories hold that the divergence between the exchange rate and the purchasing power parity is due to the supply and demand for financial assets and the international capability.

The theory of elasticities holds that the exchange rate is simply the price of foreign exchange that maintains the balance of payments in equilibrium. For instance, if the imports of country A are strong, then the trade balance is weak.

Purchasing power parity states that the price of a good in one country should equal the price of the same good in another country, exchanged at the current rate—the law of one price.

In the wake of World War II, both Germany and Japan were helped to develop new financial systems. Both countries created central banks that were fundamentally similar to the Federal Reserve of USA. Along the line, their scope was customized to their domestic needs and they diverged from their model.