Carry Trade Strategy

Australia''s central bank had its cash rate at 5.5%. Japan''s central bank had its interest rate at essentially zero. The interest rate differential was over 5%.

Every night he held a long AUD/JPY position, Australian dollars bought with borrowed Japanese yen, the difference in interest rates was credited to his account. He was being paid to hold the position. Not from price appreciation. Just from holding it. Every single night.

Over the course of 2005 and 2006, AUD/JPY also appreciated significantly as global risk appetite was healthy and capital flowed toward the higher-yielding Australian dollar. He made money twice, once from the daily carry income and once from the price movement.

This is the carry trade. One of the most distinctive strategies available in currency markets, a strategy where the position itself generates income simply from existing, before a single pip of price movement is considered.

A positive swap means you are being paid to hold the position. A negative swap means you are paying to hold it. The carry trade specifically seeks positions where the swap is positive, where the interest rate of the currency you are long is higher than the interest rate of the currency you are short.

The currencies most commonly used as the funding side, the currency you borrow and sell, are the Japanese yen and the Swiss franc. Both have historically maintained very low or near-zero interest rates.

The specific pairs that offer the best carry opportunity change over time as central bank policies evolve. The key input is the interest rate differential. The wider the gap between the two countries'' rates, the larger the daily carry income.

Capital flows toward the higher-yielding currency. As traders and institutions set up carry trades, they are collectively buying the high-yield currency and selling the low-yield currency. This buying pressure supports the high-yield currency''s price, generating not just carry income but also capital appreciation. The two sources of return build on each other.

Carry trades work best during periods of low volatility and positive global risk sentiment. When markets are calm, investors are comfortable taking on the risk of currency exposure for the sake of the daily interest income. The carry is the reward for accepting that risk.

The Sydney trader''s AUD/JPY position ran profitably for most of two years. The daily carry payments accumulated into a meaningful contribution. The price appreciation added to the total return. Both sources of income arrived simply because he held the position.

In the weeks that followed, AUD/JPY fell more than 40%.

What happened is called the carry trade unwind. When genuine fear enters global markets, when institutions that have been running carry trades simultaneously decide the risk is no longer worth the reward, they all rush for the exit at the same time. They sell AUD and buy back JPY. This surge of JPY buying is why the yen surges violently in every risk-off crisis.

The unwind is self-reinforcing. As AUD/JPY falls, it triggers stop losses on other carry traders'' positions, who then sell AUD and buy JPY, pushing the rate lower, triggering more stops. The cascade can take a position that has been profitable for months and turn it sharply negative in days.

This is the risk that must be understood and sized for before entering any carry trade. The daily income is small and accumulates slowly. The potential reversal is large and arrives fast.

The first is the yield differential. When the high-yield country cuts rates or the low-yield country raises rates, the differential narrows. Narrowing differentials reduce the daily income and often signal that institutional carry positions will begin to reduce, increasing the risk of an unwind. Watching central bank outlooks in both countries is essential.

The second is global risk sentiment. Carry trades unwind during risk-off events. Monitoring the signals covered in earlier modules, the VIX, equity market performance, credit spreads, gives early warning of deteriorating conditions that typically precede carry trade unwinds.

Position sizing for carry trades must account for the asymmetry between accumulation and reversal. The daily carry income is fractions of a percent. The potential unwind is many percent in a short period. A position large enough to generate meaningful carry income is almost certainly too large to survive a significant unwind. Carry traders who successfully manage this strategy over long periods invariably size conservatively.