When a central bank changes its policy rate, share prices move — usually before the decision, often in the direction nobody expected. The mechanism is not mysterious. Interest rates change the price of money, and every share is valued against the alternative of simply lending money instead.
Four channels do most of the work. Understanding them explains both why markets fall when rates rise, and why they sometimes do the opposite.
Channel one: the alternative return
Every investor faces a choice between owning a business and lending at interest. When short-term government securities pay very little, equities look attractive almost by default. When they pay a substantial return, the comparison changes sharply.
This matters more in African markets than in developed ones, because policy rates here have been materially higher and government securities genuinely compete with shares for domestic savings. A domestic investor who can earn a high, relatively secure return on a treasury bill needs a compelling reason to accept equity risk instead.
So when rates rise, money tends to move from equities into fixed income — not because companies became worse, but because the alternative became better. See treasury bills in Ghana for how that alternative works.
Channel two: the cost of corporate borrowing
Higher rates raise the cost of debt. The effect falls unevenly, and that unevenness is where the useful analysis lives:
| Company type | Effect of rising rates |
|---|---|
| Heavily indebted, floating rate | Interest costs rise immediately; profits fall directly |
| Heavily indebted, fixed rate | Protected until refinancing — then exposed all at once |
| Net cash on the balance sheet | Earns more on deposits; a modest beneficiary |
| Capital-intensive, expanding | Projects financed at higher rates become marginal or are shelved |
| Consumer lenders | Borrowers come under strain; bad debts rise with a lag |
Find the finance costs and the debt maturity profile in the annual report before assuming a company is unaffected. Our guide to analysing financial statements covers where those sit in the accounts and notes.
Channel three: valuation mathematics
A share is worth the present value of the cash the business will generate in future. Converting future cash into a present value requires a discount rate, and that discount rate is built on prevailing interest rates.
Raise the discount rate and the present value of distant cash falls — sharply. This is why growth companies, whose value depends on earnings expected years out, fall harder when rates rise than mature companies already generating cash today. Nothing about either business changed. The arithmetic used to price them did.
Channel four: the currency and foreign flows
Higher domestic rates make local-currency assets more attractive to foreign investors, which can support the currency and draw in portfolio capital. That is the textbook effect.
The complication is that African markets are also exposed to rates set elsewhere. When US rates rise, capital tends to leave emerging and frontier markets regardless of local policy — a Ghanaian or Kenyan market can face outflows while its own central bank is doing nothing at all. For a foreign investor the return is the share move plus the currency move, so currency and rates are tangled together. See what drives the cedi.
Why banks are the exception
Banks are not simply victims of higher rates; in several respects they benefit, which is why bank-heavy indices can behave quite differently from the broad market.
- Net interest margin. Banks lend at higher rates than they pay depositors. When rates rise, lending rates often reprice faster than deposit rates, widening the margin.
- Securities holdings. African banks typically hold large portfolios of government paper. Higher yields on new purchases lift interest income — though existing fixed-rate holdings fall in market value.
- Credit quality, eventually. Sustained high rates strain borrowers, and non-performing loans rise with a lag. The early benefit can reverse later.
Because of this, a financial-sector index and a broad market index can diverge after a rate decision. In Ghana you can watch exactly that in the gap between the two published indices — see the GSE Composite and Financial Stocks indices and how to analyse listed banks.
Why markets move before the decision
This is the part that confuses people most. Markets price expectations, not announcements. By the time a central bank raises rates, the market has usually spent weeks anticipating it.
The consequence: what moves prices is the surprise, not the decision. A rate rise that was fully expected may produce no reaction, or even a rally if the market feared something worse. A rate held steady when a cut was expected can cause a sell-off. Reading a market reaction therefore requires knowing what was already priced in — which is also why predicting these reactions is so unreliable.
What to watch across the markets we track
Each country has its own rate-setting body and its own calendar:
| Market | Monetary authority |
|---|---|
| Ghana — GSE | Bank of Ghana, Monetary Policy Committee |
| Nigeria — NGX | Central Bank of Nigeria, Monetary Policy Committee |
| South Africa — JSE | South African Reserve Bank, Monetary Policy Committee |
| Kenya — NSE | Central Bank of Kenya, Monetary Policy Committee |
| Egypt — EGX | Central Bank of Egypt, Monetary Policy Committee |
| Morocco — BVC | Bank Al-Maghrib |
Also watch the US Federal Reserve. Its decisions shape global capital flows and therefore affect all six of these markets, irrespective of what their own central banks do.
What this does not mean
It does not mean sell equities when rates rise. The relationship is real but not mechanical, and it is routinely swamped by other factors — commodity prices, politics, corporate results, global sentiment. Many rate rises have been followed by rising markets.
It does not mean rates predict markets. If the relationship were reliable, it would already be priced in. Which it largely is.
The practical use of this knowledge is positioning and expectation-setting: knowing which of your holdings carry significant debt, which earn more when rates rise, and which are valued mostly on distant future earnings. That is a portfolio you understand, rather than a forecast you are betting on.
In short
Rates change the alternative return, the cost of corporate debt, the arithmetic of valuation and the direction of foreign capital. Banks often benefit while indebted and growth companies suffer. And markets move on surprises, not announcements — so the decision matters less than how it compared with what was already expected. Check the live market overview around decision dates and watch which sectors actually moved.
