Why Currencies Move
Exchange rates are prices, set by the balance of people wanting to buy a currency against those wanting to sell it. Four forces explain most of the movement, and all four are observable if you know where to look.
Head of Fixed Income Research · · 2 min read
Illustrative sample. This guide was written to demonstrate FlowWealth’s publication format and is not a published research view. Figures are illustrative and must not be relied upon for any decision.
What is it?
An exchange rate is simply the price of one currency in terms of another. Like any price, it is set by supply and demand. When more people want to buy cedis than sell them, the cedi strengthens. When the reverse holds, it weakens. Every explanation of currency movement reduces to identifying what is changing the balance between those two groups.
Why does it matter?
In an import-dependent economy the exchange rate reaches almost everything: the price of fuel and therefore transport and therefore food; the cost of imported medicines and machinery; the cedi burden of foreign-currency debt; and the value of any savings intended for foreign-currency spending. For Ghanaian businesses and investors, currency is rarely a peripheral consideration.
A Ghanaian example
Ghana exports gold and cocoa, receiving dollars. It imports fuel, machinery and food, paying dollars. When gold prices are strong, more dollars arrive, and those dollars are converted into cedis to pay local wages and taxes — demand for cedis rises and the currency is supported. When fuel prices spike, importers need more dollars, sell cedis to buy them, and the currency comes under pressure. Much of the cedi's behaviour in any given period can be traced to which of these two flows is dominant.
The numbers
- Trade flowsImports create currency supply
- Exports create currency demand
- Interest rate differentialThe carry that supports a currency
- Higher local rates attract capital
- Inflation differentialOver long periods, this dominates
- Higher local inflation implies depreciation
- ReservesBest measured in months of import cover
- The central bank's capacity to intervene
- ConfidenceThe hardest factor to observe in advance
- Expectations become self-fulfilling
The four forces, in order of horizon#
Over years, inflation differentials dominate. If Ghanaian prices rise faster than American prices, the cedi must weaken against the dollar over time or Ghanaian goods become progressively uncompetitive. This is the gravitational pull underneath everything else, and it is why a country with persistently higher inflation will have a persistently weakening currency regardless of policy.
Over quarters, trade and capital flows dominate. Export receipts, import bills, remittances, portfolio inflows and outflows determine who is buying and selling in any given period.
Over weeks, interest rate differentials matter. When a country offers substantially higher rates, capital is attracted to earn the difference. This is the carry, and it supports the currency for as long as the differential is wide enough to compensate for the risk.
Over days, confidence dominates everything. If enough people expect depreciation, they buy dollars now — which causes the depreciation they expected. This reflexivity is why currency crises happen quickly and why they are so difficult to arrest once underway.
Why intervention has limits#
Central banks can sell reserves to buy their own currency, supporting the rate. This works, and it works only while reserves last.
The market can see the reserve position. If reserves are falling steadily to defend a level, participants draw the obvious conclusion about how long the defence can continue — and position accordingly, accelerating the outcome.
This is why months of import cover is the number worth watching rather than the exchange rate itself. The rate tells you where things are. Reserve cover tells you how much capacity exists to keep them there.
What to do about it#
For most readers the answer is not to forecast.
It is to identify your exposure — do you earn or spend in foreign currency, do you hold foreign-currency debt, are you saving toward a foreign-currency expense — and then to ask what a 20% move would do to you.
If the answer is "not much", you can stop thinking about it. If the answer is "that would be a serious problem", then the time to address it is now, while the rate is stable, rather than during the move.
Common Mistakes
- Treating depreciation as automatic evidence of mismanagement, when it can reflect an inflation differential.
- Ignoring currency when assessing returns on cedi assets that will eventually fund foreign-currency spending.
- Assuming a stable rate will remain stable — Ghanaian FX adjustment has historically been discontinuous rather than gradual.
- Watching the official rate while transacting at a different one.
- Confusing a strong currency with a strong economy; a firm currency can hurt exporters.
FlowWealth Takeaway
Currencies move because the balance between buyers and sellers changes. Trade flows, interest rate differentials, inflation differentials and confidence explain most of it. In Ghana, the practical response is not to forecast the rate but to know what a large move would do to your costs, revenues or savings — and to decide that while conditions are calm.
Sources
- Bank of Ghana, Exchange rate data and external sector statistics
- International Monetary Fund, Balance of payments statistics
This is financial education, not investment advice. It explains how something works; it does not recommend what you should do. What is appropriate for you depends on your circumstances, and FlowWealth does not provide personalised investment advice.
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