What Moves an Exchange Rate — and What a Currency Shift Does
Play Currency Exchange Curve →
What Moves an Exchange Rate
- Relative interest rates: Higher returns on domestic assets attract foreign capital, raising demand for the currency and pushing it up.
- Inflation differentials: Persistently faster inflation erodes a currency’s purchasing power, and over long horizons exchange rates tend to move toward purchasing power parity.
- Trade flows: Foreign buyers of exports must acquire the currency; domestic buyers of imports must sell it.
- Expectations and speculation: Currency markets are forward-looking, so anticipated policy changes move rates before the policy arrives.
- Relative growth and investment prospects: Capital moves toward economies expected to generate stronger returns.
- Safe-haven demand: During periods of stress, capital flows toward currencies backed by deep, liquid asset markets.
- Official intervention: Central banks buying or selling reserves shift supply and demand directly.
What a Stronger or Weaker Currency Does
- Export competitiveness: Depreciation makes a country’s goods cheaper to foreign buyers and tends to raise export volumes; appreciation does the reverse.
- Import prices and inflation: A weaker currency raises the domestic cost of imported goods and inputs, feeding into consumer prices — the pass-through channel.
- Real purchasing power: A stronger currency lets households buy foreign goods and travel more cheaply, a real gain often overlooked in the focus on exporters.
- Foreign-currency debt burdens: Depreciation raises the domestic-currency cost of servicing debts denominated in another currency, which is why currency crises and debt crises often arrive together.
- Adjustment takes time: Trade volumes respond slowly to price changes, so a balance can initially worsen after a depreciation before improving.
Why Governments Intervene — and Where the Limits Bite
- Motives for intervention: Smoothing disorderly moves, defending a peg, limiting imported inflation, or accumulating reserves as a buffer against future capital flight.
- Reserves are finite: Defending a currency against downward pressure means selling foreign reserves to buy your own currency, and the reserve stock can run out. Supporting a currency upward has no comparable limit, since a central bank can create its own currency without bound.
- Interest rate defense is costly: Raising rates to hold a peg imposes recession risk on the domestic economy, and markets know it.
- The impossible trinity: A fixed rate, free capital movement, and independent monetary policy cannot all be maintained at once — something must give.