A carry trade is a foreign exchange strategy that exploits interest rate differentials between two currencies. The trader borrows in a low-rate currency (the funding currency) and invests the proceeds in a higher-rate currency or asset (the target), earning the spread as profit.

Mechanics

The return on a carry trade has two components:

  1. Interest rate differential — the yield earned on the target minus the cost of borrowing in the funding currency
  2. Currency movement — gains if the target currency appreciates, losses if it depreciates

Because the interest differential is typically small (1–3% per year), carry traders generally use significant leverage to make the strategy worth running. This leverage amplifies both gains and losses.

Why the yen

Japan's central bank held rates at or near zero for most of 2000–2024. This made the yen the world's preferred funding currency: cheap to borrow, generally stable in a low-volatility environment, and supported by Japan's current account surplus.

At peak (mid-2024), total estimated carry positions in JPY were in the hundreds of billions of dollars.

The unwind problem

When carry trades unwind, they do so violently. Because:

  • Positions are typically leveraged
  • Many participants run similar books
  • Margin calls force selling of target assets, not just buying back funding currency
  • The resulting correlation spike hits apparently unrelated markets

The 2024 unwind caused the VIX to spike to 65 and the Nikkei to fall 12% in a single session.

How The Glitch monitors it

The YEN CARRY composite score tracks seven signals for carry trade stress. See The Yen Glitch theory → for the full methodology.