Foreign Exchange
The deepest market in the world: exchanging one currency for another, today or at a date in the future.
The market at a glance
Foreign exchange is the deepest market humanity has built: roughly $7.5 trillion of turnover every day (BIS survey), running 24 hours from Wellington's open to New York's close, with no central exchange — just a global dealer network stitched together by arbitrage. The dollar stands on one side of ~88% of all trades; EUR/USD alone is the most traded instrument on the planet.
Every cross-border activity ends here: trade invoicing, investment hedging, tourism, central-bank reserves, and speculation layered on top. The professional core is concentrated — a handful of bank dealers and non-bank market makers intermediate most flow, increasingly by internalising it (netting clients against each other) before touching public venues.
The one law of FX pricing
Covered interest parity: a forward exchange rate is not a forecast — it is spot adjusted for the two currencies' interest gap, enforced by arbitrage. High-rate currencies trade at forward discounts; low-rate at premiums. This single relation prices forwards, FX swaps and the funding structure of global finance:
What the symbols mean
- Fthe forward or futures price
- Sthe price of the underlying today
- rthe interest rate, per year
- tautime remaining, in years
Interactive: forward rate & swap points (CIP)Practitioner
Compute the arbitrage-enforced forward for any pair from spot and the two interest rates.
- Forward rate
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- Forward points (pips)
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- Annualised carry
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Textbook CIP. In reality a cross-currency basis — the price of dollar balance sheet — shifts this by a few to dozens of basis points; see the FX swap page for why.
How the products fit together
Spot is the raw exchange. Forwards lock future rates for hedgers; NDFs do the same for restricted currencies, cash-settled offshore. FX swaps — over half of all FX volume — are really collateralised currency loans, the global dollar-funding machine. Cross-currency swaps extend that to multi-year debt transformation, letting issuers borrow wherever it's cheap and swap home.
Concepts to master
- Every position is a pair — you're never just "long euro"; you're long euro against something, funding included.
- Carry and its crashes — high-yield currencies don't depreciate as parity theory predicts (the forward-premium puzzle), rewarding carry trades that periodically unwind violently. "Up the stairs, down the elevator" is this market's oldest scar.
- The dollar smile — the dollar strengthens both in US booms and global panics; only the boring middle weakens it. Half of macro trading is a position on this smile.
- The basis is a stress gauge — when covered parity breaks against the dollar, someone's funding is on fire; central-bank swap lines exist for exactly that moment.
Interactive: carry trade arithmeticPractitioner
Borrow the low-yielding currency, park in the high-yielding one, collect the difference — until the exchange rate takes it back. The numbers first:
- Rate differential
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- Carry on equity p.a.
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- Carry in dollars
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- Breakeven depreciation p.a.
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Uncovered carry: the differential is yours only if the target currency doesn't fall by more than it. History's verdict: it usually doesn't — and occasionally it does, all at once.
Interactive: currency-hedged yieldPractitioner
A foreign bond's headline yield is not what a hedged investor earns. Subtract the hedge cost — the rate differential plus the cross-currency basis — and compare honestly.
- Annual hedge cost
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- Hedged yield
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- Pick-up vs. domestic
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- Verdict
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This single calculation drives trillions of cross-border bond flows: when hedging costs exceed the yield advantage, Japanese and European institutions stop buying US bonds — and the flow reverses. See basis swaps for why that last input exists.
Go deeper
Deep diveCarry: up the escalator, down the elevator
The carry trade has beaten textbook theory over most long samples — with a return shape that explains why: steady gains, brutal unwinds.
- Theory says it shouldn't work (uncovered interest parity); practice says it mostly has — until it very suddenly hasn't.
- The unwinds cluster with vol spikes: everyone exits the same crowded trade at once.
- Funding currencies soar in crises — yen 2008 and August 2024 doubled the pain exactly when risk assets fell.
- The calculator above shows the arithmetic; this chart shows the distribution it hides: negatively skewed, crash-prone, correlated when it matters.
Deep diveExchange rates: anchored, but on a long rope
Purchasing-power parity works — on a timescale useless for trading. Currencies swing 20–40% around fair value in multi-year cycles.
- Months: rate differentials and risk appetite drive currencies (hence carry).
- Decades: PPP wins — long-run "forecasts" cluster near it.
- Corporates: hedge cash flows, not opinions.
- Investors: unhedged foreign assets carry a second, largely unrewarded bet on top of the first.
Deep diveHow the FX market actually runs
There is no FX exchange — $7.5tn a day trades through a decentralised dealer network, around the clock, with liquidity following the sun.
- Deep end: London afternoon overlapping New York. Puddle: late NY afternoon — where flash crashes live (the 2019 yen move took 7 minutes on holiday-thinned books).
- CLS settlement: both legs exchange simultaneously (payment-versus-payment), killing Herstatt risk — trades outside it (many EM pairs) still price the old danger.
- The 4pm London fix is the benchmark funds reference — site of the 2013 rigging scandal, now surveilled.
- Conventions are tribal: EUR/USD 1.10 = 1 euro costs $1.10; pips are the 4th decimal (2nd for yen); reading a quote backwards is the classic rookie loss.
Deep diveMilestones: five decades of floating
The FX market as we know it is younger than it looks:
- 1944–71 — Bretton Woods: fixed rates, until Nixon closes the gold window and the system dissolves.
- 1973 — floating begins; so does the modern FX market.
- 1974 — Herstatt fails mid-settlement: the risk that eventually creates CLS (2002).
- 1985/87 — Plaza and Louvre Accords: coordinated intervention's high-water mark.
- 1992 — Black Wednesday: Soros vs. the Bank of England; sterling leaves the ERM.
- 1997–98 — Asian crisis: pegged currencies break in sequence; reserves doctrine changes forever.
- 1999 — the euro merges eleven currencies — the largest monetary event since Bretton Woods.
- 2015 — the SNB abandons the franc floor: 30% in minutes, brokers bankrupted, "pegs break" relearned.
- 2010s–now — electronification: algos and platforms carry most flow; flash crashes (2016 GBP, 2019 JPY) are the new failure mode.
Interactive: position sizing from riskPractitioner
The professional habit that separates survivors from statistics: size the position from the risk, never the other way round.
- Money at risk
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- Position size
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- Notional
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- Effective leverage
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Size = risk ÷ (stop × pip value). Note what the formula does: a tighter stop permits a larger position for the same risk — and a stop is not a guarantee; gaps fill worse than triggers (see the flash-crash fold above).
Deep diveWho runs this market
- The dealer banks: a handful of institutions — JPMorgan, UBS, Deutsche Bank, Citi, State Street among them — intermediate most global volume. There is no exchange to overrule them.
- Primary venues: EBS and LSEG Matching for interbank majors, plus the banks' own single-dealer platforms and multi-dealer venues (360T, FXall, Hotspot).
- CLS: settles both legs of a trade simultaneously for the major currencies, eliminating the risk that ended Herstatt Bank in 1974.
- Central banks: participants, not just supervisors — intervention, reserve management and swap lines all move this market directly.
- The Global FX Code: a voluntary conduct standard written after the fixing scandals; adherence statements are public and reputationally binding.
- Where the data lives: the BIS Triennial Survey is the authoritative measure of market size; central banks publish reserves and intervention data; the CFTC's weekly positioning report is the only public positioning gauge in FX.
Deep diveNumbers & conventions worth memorising
| Item | Convention |
|---|---|
| Market size | Around $7.5 trillion a day at the last BIS Triennial Survey — the largest market on earth |
| Quoting | Base/quote: EUR/USD 1.1000 means one euro costs 1.10 dollars |
| Pip | The fourth decimal for most pairs; the second decimal for yen crosses |
| Spot settlement | T+2 for most pairs; T+1 for USD/CAD |
| Session depth | Deepest in the London afternoon overlapping New York; thinnest after the New York close — where flash crashes live |
| The fix | The 4pm London benchmark, calculated over a window and used by funds and corporates worldwide |
| Forwards | Quoted in points added to or subtracted from spot, not as outright rates |
The discipline that matters more than any forecast: hedge cash flows on their own timetable. Currency views change weekly; an invoice's due date does not.
Analysis
AnalysisThe analyst's checklist
- What exposure exists already? Most FX decisions are about a position you did not choose — foreign revenue, foreign assets, a foreign invoice.
- What do the forwards already say? The rate differential is priced; your view has to differ from the forward, not from spot.
- What regime is this currency in? Free-floating, managed, or pegged — the third looks stable right up until it does not.
- Is the trade crowded? The weekly futures positioning report is the only public gauge; extremes precede unwinds.
- What is on the calendar? Central-bank meetings, elections and the month-end fix move currencies more than fundamentals do intraday.
- Can I survive the path? Being right after a 10% adverse move only matters if the position still exists.
AnalysisRed flags
- Getting the quote direction backwards — every FX career includes this once; make it a small once.
- Treating carry as income: it is compensation for a rare, violent loss, and it prices like one.
- Pegs described as stable — the Swiss franc floor held for three years and then moved 30% in minutes.
- Unhedged foreign assets as an accidental currency bet layered on the investment thesis.
- Trading the thin session: liquidity after the New York close is where flash crashes happen.
- Emerging-market yields that look irresistible — check whether the currency is convertible before admiring the carry.
Cross rates and the triangle
Any two currencies quoted against a common third imply a rate between themselves. If the directly quoted cross differs from the implied one, the three legs can be traded round in a circle:
Interactive: implied cross rate and triangular arbitrageStarter
- Implied cross
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- Quoted cross
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- Gap
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- Gross on $1m
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- Reading
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In liquid majors this arbitrage was closed by machines decades ago and any visible gap is inside the spread you would actually pay — run it through the trading-cost calculator before believing it. Its lasting use is as a consistency check: a cross that will not reconcile with its two legs is usually a stale or mis-keyed quote.
Market mapWho is on the other side of your trade
Prices are made by participants with different jobs, different constraints and different reasons to trade. Knowing whose need you are meeting explains more about a market than any indicator.
- Corporates hedging trade flows are the only participants with a genuine underlying need. They are price-takers on timing and the reason the market exists.
- Central banks manage reserves and occasionally intervene. Their size makes them the one participant that can move a major pair by decision rather than by flow.
- Real-money asset managers hedging foreign bond and equity holdings generate large, calendar-driven flows around month-end rebalancing.
- Algorithmic market makers supply most of the visible liquidity and withdraw it in seconds when volatility spikes — which is why FX gaps rather than slides.
- Speculators are a smaller share than folklore suggests, and concentrated in the carry trade, whose crowding is measurable and whose unwind is violent.
Costly mistakesThe five mistakes that cost the most here
Not a list of ways to be clever — a list of the errors that recur, why each one is structural rather than careless, and which tool on this site settles it.
- Reading the quote backwards. The first currency is the base. Getting this wrong is the most common error in FX and it inverts every conclusion.
- Chasing the interest differential. Covered interest parity says the forward already reflects it. What is left is an uncompensated bet on the spot rate — see the carry tool.
- Leaving a foreign holding unhedged by default. Not hedging is a position, taken by omission. Decide it explicitly.
- Assuming a peg is a fact. A managed rate is a policy that can end in one minute, as 2015 demonstrated. Suppressed volatility is stored volatility.
- Underestimating the conversion spread. On a retail platform the FX charge is frequently the largest single fee paid and the least itemised.
Test yourself: five questions
Five quick questions on this asset class — checked entirely on your device, nothing stored or sent. Wrong answers come with explanations; the deep dives above hold every answer. For education only.
The Foreign Exchange product shelf
FX Spot
Exchanging one currency for another, settled in two days — the deepest market humanity has built.
Explore →FX Forward
Lock an exchange rate for a future date — the corporate world's everyday currency hedge.
Explore →FX Future
The exchange-traded twin of the FX forward — same economics, public prices, a clearing house instead of a credit line.
Explore →Non-Deliverable Forward
A forward for currencies you can't take home — settled in dollars against an official fixing.
Explore →FX Swap
Borrow one currency against another: the invisible $4-trillion-a-day funding machine of global finance.
Explore →Cross-Currency Swap
Swap debt from one currency into another for years at a time — principal, interest and all.
Explore →Concepts, comparisons and case studies about foreign exchange
- How to Size a PositionStart herePlaybooksThe decision that determines outcomes more than any view, made by almost everyone in the wrong order
- The Asian Crisis, 1997Start hereCase StudiesCurrency pegs, borrowing in a currency you do not earn, and the fastest reversal of capital flows on record
- The Swiss Franc Floor, 2015Start hereCase StudiesA central bank promised a floor for three years, repeated the promise weeks before abandoning it, and moved a major…
- Currency-Hedged vs. UnhedgedSome background helpsCompareHedging removes a risk and adds a cost, and which one dominates depends entirely on the asset
- Risk MeasuresSome background helpsConceptsTurning "how bad could it get" into a number — and knowing exactly how that number lies to you
- VolatilitySome background helpsConceptsFinance's stand-in for risk: measured from the past, traded in the present, feared about the future — and an asset…