Monetary Policy & Exchange Rate Policy (Cambridge (CIE) A Level Economics): Revision Note

The link between monetary policy and exchange rate policy

• Monetary policy uses interest rates and money supply controls to influence aggregate demand and inflation

• Exchange rate policy manages the value of a currency to influence trade balance, inflation, and competitiveness

• The two are causally linked - interest rate changes drive capital flows that affect the exchange rate, and exchange rate management often relies on monetary policy tools

Recap from AS

• The AS syllabus covers the basic tools and effects of both policies

  • Interest rates as the central bank's main tool

  • Expansionary vs contractionary monetary policy

  • Fixed, managed and floating exchange rate regimes

  • Simple effects of currency appreciation and depreciation

• This page builds on that foundation and adds the transmission mechanism in detail, quantitative easing, and the integrated effectiveness analysis of both policies across multiple macroeconomic objectives

The monetary policy transmission mechanism

• The transmission mechanism is the chain of cause-and-effect through which a change in the central bank's policy interest rate affects aggregate demand, output, employment and the price level

• The diagram below maps the full mechanism

  • Base rate changes flow through four transmission channels

  • Channels feed into demand components, which converge into aggregate demand

  • Aggregate demand drives domestic inflationary pressure, which feeds inflation

  • The exchange rate channel also affects inflation directly via import prices, separate from the AD route

A rise in the base rate transmits through the four channels as follows

• The bidirectional arrows in the diagram show the channels also interact

  • For example, expectations of higher rates can themselves drive asset prices and the exchange rate before official rate changes occur

• The combined effect of a rate rise is a fall in aggregate demand

  • The reverse applies for a rate cut

Time lags and limitations

• The full effect of a rate change typically takes 12 to 24 months to materialise

• Channels work at different speeds

  • Exchange rate effects appear within weeks

  • Market interest rate effects on consumption build over months as fixed-rate deals expire

• The mechanism may break down at the zero lower bound (the liquidity trap, covered in 9.4.7)

• Channels can be disrupted when commercial banks are repairing damaged balance sheets and fail to pass on rate changes (a key issue post-2008)

Quantitative easing

• Quantitative easing is a monetary policy tool in which the central bank creates new reserves electronically and uses them to buy financial assets (typically government bonds), expanding the money supply and reducing long-term interest rates

  • QE works through the same transmission mechanism but operates on long-term rates rather than the short-term base rate

  • Bond purchases push prices up and yields down, feeding into the asset prices channel and indirectly into market interest rates

  • QE is used when conventional monetary policy reaches its limits - typically at the zero lower bound

  • It was used extensively after the 2008 financial crisis and during the COVID-19 pandemic by major central banks

Limitation

• QE may inflate asset prices (housing, equities) more than it stimulates real activity creating distributional concerns and asset bubble risk

Exchange rate policy

• Exchange rate policy is the use of central bank intervention, interest rate adjustments, or capital controls to influence the external value of a currency in pursuit of macroeconomic objectives

  • It operates on the exchange rate channel of the transmission diagram directly

Three regime types

The link with monetary policy: the impossible trinity

• Monetary policy and exchange rate policy are not independent tools

• They both operate through the exchange rate channel shown in the transmission diagram

  • A central bank cannot simultaneously control the interest rate and the exchange rate under free capital mobility - this is the impossible trinity (or trilemma)

    • Choosing a fixed exchange rate means giving up monetary policy independence

    • Choosing monetary policy independence means accepting exchange rate volatility

  • Most major economies operate floating exchange rates to preserve monetary policy independence

Effectiveness across macroeconomic objectives

• Monetary policy and exchange rate policy work through different (but overlapping) channels and produce different effects across each objective

• The key insight is that the same policy serves different objectives through different transmission paths, and these paths often conflict

  • For example, raising rates to control inflation worsens the BoP through the same exchange rate channel that anchors expectations

Strengths and limitations