Most of the time, central banks move interest rates in small, predictable steps of a quarter of a percentage point. So when traders start talking about a half-point hike, it is a sign that inflation worries have intensified. This week, after hotter US inflation figures, markets began putting real odds on the Federal Reserve raising rates by half a point in December. Here is what that means and why it matters.
Basis points made simple
Interest rate changes are usually measured in basis points. One basis point is one hundredth of a percentage point, so 25 basis points equals 0.25 per cent and 50 basis points equals 0.5 per cent. A half-point hike is therefore a 50 basis point increase: for example, moving a rate range from 3.75 to 4 per cent up to 4.25 to 4.5 per cent.
For a homeowner or business, that means borrowing costs rise twice as fast as they would with a standard quarter-point move.
Why central banks usually move slowly
Central banks prefer gradual moves because changes in interest rates take time to work through the economy, often a year or more. Small steps let policymakers watch the effect and adjust. They also avoid shocking markets, which can tighten financial conditions far more than intended.
A quarter-point move has become the standard step for both the Federal Reserve and the Bank of England in normal times.
When a half-point move comes into play
Central banks reach for bigger moves when they think they are behind the curve, meaning inflation is running hotter or proving more persistent than expected. A half-point hike is a way of catching up quickly and signalling seriousness. The Fed used 50 and even 75 basis point moves in 2022 when inflation surged.
The decision often depends on a handful of data releases, particularly consumer and producer prices, and on the tone of key policymakers. When influential officials argue for faster tightening, markets quickly adjust the odds. Our guide to hawkish and dovish language explains how to interpret those signals.
How markets react
The main effect comes before the decision, as markets price in the possibility. Short-term government bond yields tend to rise first, because they are most sensitive to central bank rates. The currency often strengthens, since higher rates attract money from abroad. Shares, especially expensive growth stocks and smaller companies, tend to come under pressure because future profits are worth less when borrowing costs rise.
On the day itself, the surprise is what counts. If a half-point move is fully expected, markets may barely react, or even rally if the central bank sounds less aggressive about the future. If it comes out of the blue, the reaction can be sharp. Traders watch fed funds futures to see how much is priced in.
What it means for UK traders
A bigger Fed move tends to strengthen the dollar against the pound and push up global bond yields, including UK gilts. That can feed through to UK mortgage pricing and put pressure on shares sensitive to interest rates, such as housebuilders and property companies.
A beginner’s takeaway
A half-point hike is a central bank pressing the accelerator on tightening. The key for traders is not the size of the move alone, but how much the market already expects. Always compare the decision with what was priced in beforehand, and remember that the guidance on future moves often matters more than the move itself.
If you want to understand how your own trading copes with big central bank days, take our free Trader Assessment and get a clear picture of your strengths and gaps.
