How a carry trade unravels, starting with the cheapest money in the world

A carry trade is a simple idea with a complicated exit: borrow where money is cheap, invest where it pays more, collect the difference. Its profit is quiet and its unwind is loud, because the positions built over years are financed short and margined daily. The Bank of Japan's September rate rise reduced the spread that made the yen the world's favourite funding currency, and the question that follows is not whether the trade unwinds but in what order and at whose expense. The mechanics are public, and they explain who moves first.

By Muhammad MehdiPublished 9 October 2026 at 08:00 UTC· Updated 9 October 2026 at 08:00 UTC· 4 min read

The yen has financed the world's risk positions for a generation, not because anyone designed it that way but because Japan's interest rates were the lowest among major currencies for long enough that a habit formed. The habit spread from currency funds to insurance companies to retail households, and each participant borrowed in the same currency to buy the same kinds of assets abroad. That uniformity is what makes the unwind matter: a trade held by many hands in the same shape exits in many hands at once.

The trade in practice

The basic structure is an exchange and two interest rates. A holder converts borrowed yen into a foreign currency and buys a bond, a deposit or an asset that pays more than the yen loan costs. Two numbers decide the profit. The rate spread is the annual income. The exchange rate is the risk, and it is the risk that dominates: a move against the position of a few percent can erase a spread that took a year to accrue.

The popular version of the story is a leveraged fund in a low-tax jurisdiction. The larger version is institutions. Japanese life insurers and pension funds have invested heavily in foreign bonds, often without currency hedges, because hedging costs consumed the yield advantage for years. When unhedged positions are marked to market, a stronger yen reduces the yen value of every foreign asset on the book, which imposes losses that do not care whether the holder calls itself a carry trader.

What the rate rise changed

The Bank of Japan's September increase raised the funding rate, narrowing the spread that makes the trade work, and it did something subtler: it made the market reconsider the direction of travel. Carry positions are not sustained by the current spread alone. They are sustained by the expectation that the spread persists, because a trade that returns a couple of percent a year needs stability to be worth holding. A credible tightening cycle raises the probability that the funding leg gets more expensive every quarter, which raises the bar for staying in.

Hedging costs moved with the same logic. For Japanese institutions, the cost of hedging dollar exposure is the rate difference between the two currencies. As yen rates rise, that cost falls, which sounds helpful, but it also means the unhedged trade's advantage shrinks. The two effects push in opposite directions, and the net is that the marginal dollar of foreign investment becomes less attractive exactly when the positions already in place have to be reviewed.

The mechanics of the exit

Unwinds are a sequence, and the sequence has a pattern.

It usually begins with the most leveraged holders, because margin calls arrive first at whoever borrowed most against the least collateral. Their selling of invested assets and closing of currency positions strengthens the yen, which creates losses for the next most leveraged layer, which sells in turn. The phases are compressed: the visible move in a significant unwind tends to happen over days, while the repositioning of slower holders continues for months.

Along the way the volatility itself becomes a participant. Higher implied volatility raises the cost of hedging and of options protection, which removes the instruments that make positions holdable. Dealers widen spreads and reduce balance sheet committed to currency markets precisely when liquidity is most needed. And because many participants measure risk the same way, they receive the same signals to reduce at the same time.

What the real economy sees

The yen carry trade is a financial structure, but its unwinding transmits. A stronger yen makes Japanese exports more expensive and imports cheaper, redrawing margins for the country's manufacturers and easing some of its consumer pressure at once. Japanese institutional selling of foreign bonds pushes up yields abroad, tightening borrowing costs in markets that had nothing to do with the trade. Equity volatility rises across regions because the asset side of the trade spans the world.

For countries that host the investments, the visible symptom is usually a funding market episode rather than a trade crisis: cross-currency basis widens, foreign investors sell bonds, and currencies that were popular carry destinations depreciate. Each of those was observed in the episodes of the past two years, and each is a mechanical consequence rather than a policy statement.

Reading the next phase

Three quantities frame what comes next. The first is the pace of the Japanese tightening itself, since it sets the funding cost's trajectory. The second is the size of unhedged foreign holdings on Japanese institutional balance sheets, which decides how much repositioning is still available to do. The third is volatility, because the trade cannot be held in size when the price of insuring it exceeds its return.

None of the three is hidden. The central bank publishes its decisions, the balance sheets appear in statistics, and the market prices the volatility continuously. What is not visible is when the layers decide to move relative to each other, and that timing is the entire difference between a gradual repricing that the financial system absorbs and a compressed unwind that it feels as a shock.

Frequently asked questions

What is the yen carry trade, in one sentence?

Borrowing yen at Japan's low interest rates and using the proceeds to buy assets that yield more elsewhere, keeping as profit the difference between the two rates, as long as the exchange rate does not move against the position by more than that difference.

Why did the September rate rise matter?

Because the trade's profit is the spread between funding and investment rates. Any rise in yen rates narrows that spread directly, and any signal that Japanese rates will keep rising makes the funding leg more expensive to hold. The trade does not need the spread to vanish to become unattractive; it only needs the spread to shrink enough that a modest exchange rate move wipes out the year's carry.

Who actually holds carry positions?

More participants than the stereotype suggests. Foreign exchange focused hedge funds hold leveraged positions and are the fastest movers. Japanese life insurers, pension funds and bank treasuries hold unhedged foreign bonds on a scale that dwarfs the funds, and their decisions are slower but larger. Retail margin traders in Japan run currency positions with the same logic. The funds set the timing of moves; the institutions set the size.

What triggers the unwind, technically?

A move in the exchange rate large enough to produce losses on the invested leg while the funding cost rises. Leveraged holders facing margin calls sell the invested assets, which pushes their prices down and often triggers further calls at other holders. Because the same trade is held across many balance sheets, the selling arrives in clusters rather than as a smooth adjustment.

Does an unwind require a trigger event?

It requires a sharpening of the mismatch, which can come from an exchange rate move, a rate signal, a jump in volatility that raises hedging costs, or a funding shock abroad. The significant episodes have often combined two of those at once, which is why the loud phases are short and the quiet repositioning around them longer.

Sources

Continue reading

Economy & Markets

Where the price cap leaks: a report card on two years of capping oil

Price caps are the most elegant instrument sanctions theory has produced: instead of banning a country's oil, they allow it to flow while forcing the price down, using the services only Western markets can supply as the lever. Elegant designs leak, and this one has leaked at four identifiable seams. The war has added pressure at each of them, and the caps' future now depends on a question their architects have never fully answered: what happens when the services being withheld become optional?

Economy & Markets

How insurers price a war at sea, and why their verdict arrives late

The first market to react to a dangerous strait is not the oil market or the news cycle. It is the marine insurance market, where a small committee of underwriters decides which waters are listed areas and a handful of brokers decide what a voyage through them costs. The premiums they set are the quiet mechanism that turns a security incident into a freight surcharge, and the 2026 war has moved them more than any event since the 1980s tanker wars. Understanding how the pricing works explains why shipping keeps sailing through waters the rest of the world has written off.

Economy & Markets

August borrowing at £18.3 billion: the ONS figures that put heat on the October budget

Public sector net borrowing reached £18.3 billion in August 2026, up £2.9 billion from a year earlier and the second-highest August on record after 2020, driven by a record interest bill of £8.8 billion and a current budget deficit that the OBR now says leaves a £3.5 billion gap against the March forecast. With the Budget due on 28 October, the data show a gap between debt-service costs and receipts that the government must either bridge with new revenue or explain to markets.