El carry trade: ganar el diferencial de tipos — y pagarlo

The carry trade is one of the oldest ideas in currency markets: hold the currency that pays the higher interest rate, fund it with the one that pays less, and collect the difference for every day the position lives. At retail, that collection arrives as a nightly swap credit on your statement — visible, automatic, and seductive. This sheet explains the mechanism in full and then presents the bill that comes with it: a return profile that climbs stairs and descends in an elevator, unwind episodes that have erased years of collected differential in weeks, and a leverage interaction that makes a small rate gap anything but a small risk.

The mechanism: a rate differential collected through swap

Every overnight currency position is already a carry position, whether intended or not. Hold a pair past the daily ▲rollover and you are, in effect, lending one currency and borrowing the other — so each night your account is credited or debited the gap between their interest rates, adjusted by your broker's financing terms. That nightly line is the ▲swap, and the sheet on ▲overnight financing derives it in full. The carry trade simply chooses the direction on purpose: it picks the side of the pair where the differential pays you, and then holds.

Read the worked rows the way an accountant would. The raw central-bank differential was 2.25%, but the position collects about 1.3% — the broker's financing adjustment consumed nearly half. The same arithmetic run on the long side of this pair would pay roughly $9.80 a night rather than receive it, because the adjustment works against you in both directions. Two consequences follow. First, the carry side of a pair is whichever side the published schedule actually credits — not the side a rate table implies. Second, the collected figure is small relative to the notional: about a third of one pip per night on this pair. Keep that number in view; the rest of the sheet is about what stands on the other side of it.

Where retail meets carry: the schedule, not the story

In practice, a retail carry position lives and dies by the broker's published swap schedule. The schedule changes as central banks move and as financing terms are revised; a pair that credited shorts last quarter can debit them this quarter. Triple-swap Wednesday — three days of financing applied at once, because spot settlement crosses the weekend — triples the credit and the debit alike. None of this is hidden, and all of it is checkable, which is exactly why this sheet keeps pointing at the schedule rather than quoting one.

The historically famous carry pairs put a high-rate commodity or emerging-market currency against a low-rate funding currency — Australian dollar against yen for a generation of traders, and beyond the majors, the ▲exotic pairs: lira, rand, peso. The exotics advertise the fattest differentials and attach the fattest catches: wider spreads, thinner liquidity, and currencies whose higher rates exist precisely because markets expect them to depreciate or to carry real crisis risk. A differential of several percent against a currency that loses several percent a year is not a return — it is a treadmill with a cliff at one end. The honest read of a big swap credit is not “free money found” but “risk priced in public”.

The return profile: stairs up, elevator down

If carry returns arrived independently each day, the trade would be unremarkable. They do not. The profile is a long staircase of small credits interrupted by abrupt, deep losses — and the losses cluster, because of who is in the trade and why. A popular carry pair accumulates a crowd that all owns it for the same reason: the differential. The crowd is, in effect, short fear. When a shock arrives — any shock — the funding-currency borrowing that finances the trade has to be repaid, which means buying back the cheap currency and selling the high-yielder. Each exit pushes the price against everyone still in, triggering their exits in turn. The staircase took months; the elevator takes days.

This is the same machinery described in the risk-on, risk-off sheet, seen from inside the trade: carry is a risk-on position by construction, and the funding currencies are havens in stress largely because carry traders are forced to buy them back. The consequence for position math is brutal — the worst losses arrive together, across every carry pair at once, exactly when exits are most expensive. An average return figure hides that shape entirely. The shape, not the average, is what decides whether an account survives.

The historical unwinds: the warning label, with dates

Three yen episodes make the shape concrete; the figures below are approximate, and checking them against any long-term chart is part of the point. In October 1998, after a year of popular yen-funded trades, USD/JPY fell roughly 15% in under a week as leveraged positions unwound — a move that erased many multiples of a year's differential for anyone holding the carry side. In 2008, AUD/JPY — the emblematic carry pair of its decade — lost roughly 45% from its peak as the financial crisis forced a global unwind. And in July–August 2024, a small Bank of Japan rate rise plus soft US data unwound a crowded yen-funded complex: USD/JPY dropped about 12% in a few weeks, with the sharpest losses concentrated into days.

Note what the three episodes share. Each followed a long, calm staircase that made the trade look safe. Each was triggered by news that, in isolation, reads as minor. Each moved fastest against the most crowded pairs. And each erased years of collected swap for leveraged holders before most of them could exit. That is not bad luck visiting an otherwise sound idea — it is the idea's own mechanics, paid all at once. Any presentation of carry that shows the staircase without the elevators is showing half a chart.

Leverage and carry: a small differential is not a small risk

Now put the two halves of the sheet side by side, using the survey's standard anchor of $10 per pip on one standard lot. The worked position above collects about $3.80 a night — roughly $115 a month, $1,387 a year. The same position's price risk: a 100-pip move, an ordinary week on this pair, is $1,000 either way — nine months of swap, won or lost in days. An unwind-scale move of 300 pips against the position costs $3,000, more than two years of credits; the same 300 pips in its favor pays $3,000, and the swap line is a rounding error in both outcomes. The price leg dominates the swap leg in every realistic scenario. That sentence is the whole sheet.

▲Leverage makes the comparison sharper, not different. At 10:1, the position above is held against margin of roughly $10,850 — so the annual swap credit is about 13% of margin, which is the number carry marketing quotes, while the 300-pip unwind is 28% of margin, which is the number it does not. Both numbers come from the same position; quoting one without the other is selling, not teaching. Sized so the elevator scenario is survivable, a carry position is a deliberate macro view that pays a small rebate while you hold it. Sized to make the rebate feel like a salary, it is an unwind waiting for its date.

Where this connects: the overnight-financing sheet derives the swap line this trade is built on; the central-banks sheet explains the rate differentials that create it and the decisions that erase it; and the hedging sheet covers what holding multiple carry exposures does to a book. Read together, they reduce every carry pitch you will ever see to two checkable numbers — the rebate and the elevator — and the discipline of never quoting one without the other.