A carry trade is a currency position designed to benefit from an interest rate difference. The trader sells or borrows a currency with a relatively low interest rate, called the funding currency, and buys a currency with a relatively high interest rate, called the target currency. If the position remains open, the trader may receive positive overnight financing. However, this income is never isolated from exchange rate risk. A relatively small adverse currency move can exceed months of accumulated carry.
Funding and target currencies
The funding currency is the side used to finance the position. Traders often prefer a currency associated with lower short term interest rates because its financing cost may be lower. The target currency is the currency being purchased, usually because its interest rate is higher.
The difference between the two rates is the interest rate differential. A positive differential creates the basic economic case for the trade. For example, if the funding rate is 2% and the target rate is 6%, the gross annual differential is 4 percentage points. That does not mean a trader automatically earns 4%. Actual financing depends on the position direction, contract size, holding period, provider adjustments, administrative charges and the timing of rollover.
In retail spot forex, the trader usually does not arrange a separate bank loan. The economic effect appears through overnight financing, often called rollover or swap. Positions held beyond the daily cutoff may receive or pay an adjustment. Certain rollover days can include several days of financing to account for settlement conventions and weekends.
How the return is created
A carry trade has two main return components:
- Financing return: the overnight amount received or paid because of the rate differential and contract terms.
- Exchange rate return: the gain or loss caused by movement between the funding and target currencies.
The trade works best when the target currency stays stable or strengthens against the funding currency. It can lose money when the target currency weakens, even if the financing adjustment remains positive.
Worked hypothetical example
Imagine a $1,000 account and a hypothetical currency position with a notional value of $5,000. Assume the estimated net annual carry is 4%, after the stated financing adjustment but before trading costs.
The estimated carry for one year is $5,000 multiplied by 4%, which equals $200. For three months, a simple estimate is $200 multiplied by 3 divided by 12, which equals $50.
Now imagine the target currency falls 3% against the funding currency during those three months. The exchange rate loss is approximately $5,000 multiplied by 3%, which equals $150. Combining the two components gives $50 of carry minus $150 of currency loss, for a net loss of $100 before spreads, commissions and slippage.
The account committed only $1,000, so that $100 loss equals 10% of the account. This illustrates why position size matters. The financing income is calculated from the notional position, but adverse exchange rate movement is also applied to that larger amount.
Why carry trades unwind
An unwind occurs when traders close the position by selling the target currency and buying back the funding currency. A few traders exiting may have little effect. When many participants hold similar positions, simultaneous exits can reinforce the price movement.
Several conditions can trigger an unwind. The expected rate differential may shrink, the target currency may become more volatile, liquidity may deteriorate, or traders may reduce risk across several markets. Loss limits and margin pressure can then force additional position closures.
This process can become self reinforcing. Early selling weakens the target currency. That creates losses for other carry traders, who may also exit. Their selling adds further pressure, while demand for the funding currency increases as borrowed exposure is repaid. The result can be a rapid move that is much larger than the accumulated financing income.
Main risks and common mistakes
- Treating carry as fixed income: the financing amount may look predictable, but the exchange rate is not.
- Ignoring position size: a modest percentage move on a large notional position can create a major account loss.
- Assuming rates will remain unchanged: monetary policy expectations and market financing conditions can alter the differential.
- Checking only headline rates: the actual rollover credited or charged may differ from the simple policy rate gap.
- Overlooking negative rollover: holding the pair in the wrong direction may turn expected income into a daily cost.
- Ignoring crowded positioning: a popular carry trade may become difficult to exit when many traders react together.
- Using a tight stop without considering volatility: ordinary price movement may close the trade before carry becomes meaningful.
- Holding without an exit rule: positive financing can encourage traders to keep a deteriorating position open.
A practical carry trade checklist
- Identify which currency is the funding currency and which is the target currency.
- Confirm whether the chosen trade direction receives or pays overnight financing.
- Estimate net carry using the stated rollover terms, not only headline interest rates.
- Calculate how a 1%, 3% and 5% adverse currency move would affect the account.
- Set a position size, loss limit and exit condition before entry.
- Check liquidity, volatility and rollover timing before holding through the cutoff.
- Review the trade if the rate differential, financing charge or price trend changes materially.
Carry should be treated as one part of total return, not as protection against loss. If the position cannot tolerate a realistic adverse currency move, the expected financing income does not make the risk acceptable.
Educational content only, not investment advice. Leveraged trading can lose more than you expect.