Central banks, rate differentials and carry
How interest rates drive currencies, what a carry trade is, and why its quiet income can end in a sudden sell-off.
Why rates move currencies
Central banks set short-term interest rates to manage inflation and growth. Higher rates tend to attract capital and support a currency, while cuts can weaken it. What matters for the market is the expected path of rates relative to other countries, not only today's level. The gap between two countries' rates is the interest rate differential.
The carry trade
A carry trade borrows in a low-rate currency and invests in a high-rate one, earning the difference while the position stays open. It can produce steady income in calm markets, which attracts many traders. The same position is vulnerable: in a risk-off period, investors often unwind carry trades quickly, and the high-rate currency can fall sharply against the funding currency.
Managing the risk
Treat carry as a source of risk, not free income. Watch central bank guidance, not only current rates, and expect that a calm trend can reverse in days. Size positions for a sudden unwind, and remember that a ladder built in a carry direction adds exposure into exactly the move that may hurt most.
Key takeaways
- Rate differentials and expected rate paths move currencies.
- Carry earns a small daily return but can reverse sharply.
- Size for an unwind and watch central bank guidance, not just the current rate.