Carry Trading — Profiting from Interest Rate Differentials

The carry trade makes money from something different. Time.

Here is the idea. You borrow money in a currency with a very low interest rate, say the Japanese yen at 0.1%. You use that borrowed money to buy a currency with a much higher interest rate, say the Australian dollar at 4.5%. Every day you hold that position, you earn the difference in interest rates, approximately 4.4% annually, divided across every day you hold the trade.

You are not primarily trading price movement. You are collecting interest, called the carry, on the differential between what you are earning on your long position and what you are paying on your short position. The price of the pair can stay completely flat and you still make money from the daily interest payments.

The carry trade is a legitimate and widely used strategy employed by some of the largest funds in the world. Understanding it gives you a window into one of the most significant structural flows in the forex market.

If you are long AUD/USD, long the higher-yielding Australian dollar and short the lower-yielding US dollar, and the Australian rate is higher than the US rate, you receive a positive swap. Money is credited to your account each day you hold the position.

If you are short AUD/USD, short the higher-yielding currency and long the lower-yielding one, you pay a negative swap. Money is debited from your account each day.

The size of the swap depends on the interest rate differential between the two currencies and the size of your position. On a standard lot position where the differential is 2%, you might earn or pay approximately $55 to $60 per week simply from the swap. On a large position held for months, this adds up significantly.

Exchange rate risk.

If you are earning 4% per year from the interest rate differential, a 5% adverse move in the exchange rate wipes out more than a year''s worth of carry income in a single move. And carry trades, by their nature, are often exposed to exactly this kind of sudden reversal.

Here is why. Carry trades attract capital during periods of stability and confidence. Many traders pile into the same positions simultaneously, long the high-yielding currency, short the low-yielding one. This creates a crowded trade.

When risk sentiment suddenly shifts, a financial shock, a geopolitical crisis, a surprise central bank decision, all those carry traders unwind simultaneously. They sell the high-yielding currency and buy back the low-yielding one. The rush for the exit amplifies the move dramatically.

The Japanese yen carry trade unwind is one of the most feared events in forex markets. When yen carry trades unwind, USD/JPY can fall hundreds of pips in hours. The 2008 financial crisis and the 2020 COVID shock both triggered massive yen carry unwinds that caused extraordinary volatility across all yen pairs.

When global risk sentiment turns negative suddenly and USD/JPY or AUD/JPY falls sharply with no obvious fundamental catalyst, a carry trade unwind is often the explanation. Understanding this helps you avoid being on the wrong side of the move and potentially positions you to trade the unwind itself.

For traders who do want to incorporate carry into their approach, the key principles are straightforward. Trade in the direction of the carry, long the higher-yielding currency against the lower-yielding one. Only run the position during periods of stable or improving risk sentiment. Have a clear exit plan for when risk sentiment deteriorates. And size the position conservatively enough that a sudden exchange rate move against you does not wipe out months of accumulated carry income.