What is the yen carry trade

The carry trade is one of the oldest strategies in foreign exchange. The logic is simple: borrow in a currency with low interest rates, invest in a currency with higher rates, pocket the difference.

For most of the last two decades, the currency of choice for borrowing has been the Japanese yen. Japan's central bank — the Bank of Japan, or BOJ — held interest rates at or near zero for most of 2010–2024. At peak, you could borrow yen at 0.1% and invest in US Treasuries yielding 5%+.

Why it works — until it doesn't

The math looks clean: borrow cheap, earn expensive, collect the spread. The catch is currency risk. If the yen strengthens against your target currency, your gains are wiped out — and if the move is fast enough, the losses can be catastrophic.

For years, this risk seemed theoretical. The BOJ remained committed to ultra-loose policy. The yen weakened steadily. Positioning grew.

By mid-2024, CFTC data showed speculative short-carry trade positioning in JPY near the largest since 2007. The trade had become, in the language of risk, overcrowded.

Overcrowded trades are dangerous not because of what they do when they work, but because of what happens when they stop working. Everyone is long the same side. When the unwind starts, there is no one to buy from. The exit is a corridor with no width.

The 2024 unwind

When the BOJ raised rates by 0.25% in July 2024, the yen strengthened sharply. Carry traders — many of them levered 5-10x — faced margin calls. They had to sell their long positions (US stocks, Australian bonds, EM equities) to buy back yen.

The result was a global risk-off cascade. The Nikkei fell 12% in a day. The VIX spiked to 65. Markets that had nothing to do with Japan moved violently.

This is the defining feature of the carry trade: its unwind is contagious. Because the funding currency is yen, the collateral is global, and the leverage is extreme, when it goes, it takes everything with it.

What to watch

The Glitch monitors seven signals for carry trade stress:

1. USD/JPY spot level relative to our threshold
2. COT speculative positioning in JPY futures
3. Tokyo CPI data (leads BOJ policy decisions)
4. JPY/USD interest rate swap spread
5. JPY implied volatility (options market stress)
6. Nikkei relative to SPX (Japan risk premium)
7. FXY ETF flow data

When enough of these fire simultaneously, the composite score rises. Above 65: pay attention. Above 80: act.

See the full methodology → for weights and backtested thresholds.