4.19 - Current Account & Exchange Rate

How equilibrium exchange rates are determined

The value of a currency in foreign exchange markets is set by the forces of demand and supply, much like any other market. This interaction establishes an equilibrium exchange rate where the amount of currency bought equals the amount sold.

Factors influencing demand and supply in a simplified model

In a basic approach that focuses solely on trade, without considering financial transactions:

• Demand for a currency - Arises from foreign buyers needing the currency to purchase a country's exported goods and services.
• Supply of a currency - Comes from domestic residents who need foreign currencies to buy imported goods and services.

The equilibrium rate adjusts until demand matches supply, balancing the currency's value. The diagram below shows this simplified model for the market for pounds, with the price of a pound in euros on the vertical axis and the quantity of pounds traded per period on the horizontal axis. D for £ slopes downwards because it comes only from euro-area buyers of UK exports, and S1 of £ slopes upwards because it comes only from UK residents buying imports. The two cross at point a, giving the equilibrium exchange rate e1, at which the value of UK exports equals the value of UK imports.

How current account deficits affect currency value

A current account deficit occurs when a country's imports of goods and services exceed its exports, creating an imbalance in trade. This situation affects the foreign exchange market by altering the supply and demand for the currency.

How deficits lead to currency depreciation

• Excess supply creation - When imports surpass exports, more of the home currency is supplied to foreign exchange markets to pay for those imports, while demand from exports remains lower.
• Depreciation effect - This excess supply pushes the currency's value down, assuming other influences stay constant (ceteris paribus).
• Causes of deficits - Deficits can stem from a surge in imports or a drop in exports, both increasing the supply of the home currency.

For instance, if the UK starts buying more cars from Germany, British residents supply more pounds to obtain euros, so supply shifts right from S1 of £ to S2 of £. At the original exchange rate e1 the quantity of pounds demanded stays at point a while the quantity supplied rises to point b, leaving an excess supply of £ equal to the distance ab. That distance is both the excess supply of pounds on the foreign exchange market and the size of the current account deficit. The pound therefore depreciates from e1 to e2, where D for £ crosses S2 of £ at point f and the value of exports and the value of imports are equal once more.

How currency depreciation restores trade balance

Depreciation of a currency acts as a self-correcting mechanism in trade imbalances, making adjustments that help bring exports and imports back into line.

Effects of depreciation on trade

• Boost to exports - A weaker currency reduces the price of domestic goods for foreign buyers, enhancing competitiveness and increasing export volumes.
• Reduction in imports - Imported goods become more costly for domestic consumers, discouraging purchases and lowering import levels.
• Path to equilibrium - These changes continue until exports rise and imports fall enough to eliminate the deficit, reaching a new equilibrium where trade is balanced.

Limitations of the simplified trade flow model

While the trade-focused model explains how deficits can lead to depreciation, it overlooks broader influences on exchange rates.

Real-world complexities

• Role of financial flows - In practice, exchange rates are heavily affected by non-trade activities, such as investments in stocks, bonds, or property across borders.
• Other influences - Factors like interest rate differences, inflation rates, or speculative trading can dominate, meaning a current account deficit does not always result in currency weakening.