AZnomicsThe Yen Carry Trade
Borrow cheap in Japan, invest everywhere else — until it all unwinds at once
"A single Bank of Japan rate hike in August 2024 wiped $6.4 trillion from global markets in three days."
For three decades, Japan kept interest rates near zero while the rest of the world's rates were higher. This created one of the most consequential — and least understood — forces in global finance: the yen carry trade. Trillions of dollars were borrowed in cheap yen and invested in higher-yielding assets worldwide. When it unwinds, it does so violently — and the shockwaves reach every market on earth.
The logic is simple: borrow in Japanese yen at 0.1% interest. Convert to US dollars or Australian dollars. Invest in assets yielding 4–5%. Pocket the difference. Repeat at enormous scale. Hedge funds, banks, and even ordinary Japanese households did versions of this for decades. At its peak, estimates suggest $4 trillion or more was deployed in yen carry trades globally — a hidden leverage bomb sitting underneath world markets.
The trade is profitable as long as two things hold: Japanese rates stay low, and the yen stays weak or stable. But when Japan raises rates — or when global panic causes investors to flee risky assets — both conditions break simultaneously. Investors rush to repay yen loans, which means buying yen, which strengthens the yen, which makes the loans more expensive to repay, which forces more selling of assets everywhere. A self-reinforcing collapse. In August 2024, a single surprise Bank of Japan rate hike triggered the largest single-day Nikkei crash since 1987 and wiped $6.4 trillion from global markets in days.
To understand why rates were zero for so long, you have to understand Japan's own economic tragedy. Japan's property and stock bubble burst in 1991 — the Nikkei fell 80% and took 34 years to recover its 1989 peak. Deflation set in: prices fell, so consumers waited to buy, so businesses cut prices further, so the economy stagnated. Japan became the world's first major economy trapped in a deflationary spiral, and zero interest rates were the desperate response. Japan is the cautionary tale every central bank studies when inflation turns to deflation.
The yen carry trade is a perfect lesson in how interconnected and fragile the global financial system is. A rate decision in Tokyo moves stock markets in São Paulo. Risk doesn't disappear when you borrow cheaply — it hides, accumulates, and then surfaces all at once. The 2024 unwind was a warning. The full unwinding of decades of zero-rate borrowing has not yet happened.