Intermediateexplainers
Why Exchange Rates Move: Interest Rates, Trade, and Sentiment
Learning objectives
- Explain how supply and demand set exchange rates
- Describe the role of interest-rate differentials
- Identify how trade and capital flows move currencies
- Interpret what a stronger or weaker currency means
A price like any other
An exchange rate is the price of one currency in terms of another, set where supply meets demand in foreign-exchange markets. Demand for a currency comes from foreigners buying its exports, assets, or bonds; supply comes from residents buying foreign goods and assets. Anything shifting those flows moves the rate.
More foreign demand for domestic assets → currency appreciates; more domestic demand for foreign goods → it depreciates.
Interest rates: the big driver
Higher domestic interest rates attract foreign capital seeking yield, bidding up the currency — the carry-trade logic. But expected future rate moves matter more than today's: currencies jump on central-bank signals because markets price the path ahead. This also explains violent reversals when expectations flip.
Trade, inflation, and risk
Strong exports support a currency; persistent inflation erodes it by cutting real returns. In crises, safe-haven currencies (dollar, yen, franc) strengthen as capital flees risk — fundamentals take a back seat to fear. Speculation amplifies all of it: most FX volume is financial, not trade-related.
In the long run, exchange rates should offset inflation differences — but 'long run' can mean decades.
Strong vs weak: no free lunch
A strong currency makes imports and travel cheap but hurts exporters; a weak one boosts export competitiveness but raises import prices and inflation. Policymakers rarely get to choose — and attempts to fix rates invite speculative attack unless backed by reserves and credibility.
This article explains FX economics. It is not foreign-exchange or investment advice.
Key points
- Exchange rates balance supply and demand for currencies
- Interest-rate differentials and expectations drive capital flows
- Trade balances, inflation gaps, and risk appetite all matter
- Most FX volume is financial speculation, not trade
- Strong and weak currencies each have winners and losers
Common misconceptions
✓ Truth: It cheapens imports but harms exporters and can hollow out manufacturing.
✓ Truth: Pegs survive only with reserves, credibility, and consistent policy — otherwise speculators break them.
✓ Truth: Capital inflows financing the deficit can keep it strong for years.
Frequently asked questions
What is purchasing power parity?
The theory that identical goods should cost the same everywhere once converted — a long-run anchor, weak in the short run.
Why do currencies crash suddenly?
Pegs, debt, and politics can trigger self-fulfilling runs: everyone sells because everyone expects others to sell.
What is a carry trade?
Borrowing in a low-rate currency to invest in a high-rate one — profitable until the exchange rate moves against you.
Do central banks intervene in FX markets?
Yes, occasionally — buying or selling their currency to calm disorderly moves, with mixed success.