On August 4, 2026, the US and Japan intervened in currency markets together for the first time since 1998, buying yen to stop its slide. The yen jumped over 1% in hours. For anyone exposed to a carry trade unwind, that kind of move is the nightmare scenario — not because the yen rose, but because of how fast it happened.
A carry trade means borrowing money in a currency with low interest rates, then investing it somewhere returns are higher. Japan has kept rates near zero for years, so traders borrow yen, convert it to dollars, and buy US Treasuries or emerging-market bonds. Two things make this profitable: the interest rate gap (borrow at 1%, earn 4%, keep the difference), and the currency itself — if the yen keeps getting weaker, it costs less to pay the loan back later.
The trade works fine until the yen moves the other way. Most of these positions are leveraged — traders put down a small amount of their own money and borrow the rest. When the yen strengthens even a little, leveraged positions lose value fast, triggering margin calls: brokers demanding traders sell assets to cover the loss. Selling means dumping dollars and buying yen to repay the loan, which pushes the yen up further, triggering the next round of margin calls. That loop is why a carry trade unwind rarely trickles out — it tends to detonate.
This isn’t theoretical. On August 5, 2024, five days after the Bank of Japan raised rates, the Nikkei 225 fell 12.4% in a single session — its worst day since 1987 — as carry trade positions unwound within hours.
The same feedback loop shows up whenever forced deleveraging hits a market, and it’s the mechanic behind why the US and Japan reached for a repo facility this time instead of selling Treasuries outright. Leverage doesn’t improve the ride — it just makes both directions faster, the same lesson leveraged ETFs teach on a smaller scale every single day.
Not advice. Just how I see it.