The Carry Trade Strategy

When conditions change, whether through a risk event, a policy surprise, or a sudden move in volatility, those participants want out simultaneously. Selling the high-yielder and buying back the funding currency in size moves price against the position that everyone still holds, which triggers more exits. The result is a move that is far larger and faster than the news that started it, which is why historical carry unwinds show up on charts as near-vertical drops.

The practical implication is that the risk is not distributed evenly over time. Long quiet stretches of small daily credits are punctuated by rare, severe moves. Sizing a carry position on the calm period is how the quiet stretch pays for the violent one.

The conditions that support a carry trade, and the ones that end it

Note that three of the four hostile conditions can appear together within hours. That correlation is the point: carry does not degrade gradually, it tends to fail all at once. Central bank expectations are the variable worth tracking most closely, since they move both the differential and the sentiment at the same time. Background on how those rate decisions transmit into currencies sits in the forex primer.

Sizing a position you intend to hold for months

Because the whole point is holding, the position has to be small enough to survive drawdowns that a short-term trader would never tolerate. A few working principles:

1. Size on the adverse move, not the yield. Work out what a 5% or 8% move against the position costs the account, and decide whether that is acceptable before considering the interest.
2. Leverage is the amplifier that ruins this trade. A 4% annual carry looks unappealing unleveraged, which is exactly why carry positions are routinely leveraged, and why the unwinds are so damaging.
3. Decide the exit in advance. A stop far enough away to survive normal volatility, or a rule based on the differential narrowing, or both.
4. Treat the interest as compensation for risk, not as income. The payment exists because someone is being paid to hold an exposure others do not want.

What a carry trade is not

It is not a savings product with a currency wrapper, and the interest is not a guaranteed return, since the principal is exposed to the exchange rate the whole time. It is also not a strategy that scales down neatly, because the yield only becomes interesting at leverage, and leverage is what turns an ordinary adverse move into a serious loss.

Used deliberately, as a long-horizon position sized for a bad month and monitored against central bank expectations, it is a coherent approach with a clearly identified risk. Used as a way to collect steady daily credits without thinking about the exchange rate, it has a long history of ending badly for the people holding it when conditions turn. The glossary covers swap, rollover and the related terms in more detail.