FX Option
Also known as: Currency option, Vanilla FX option
The right to exchange currencies at a set rate — hedging with the upside left open.
1 · SnapshotThe one idea to remember
2 · BeginnerWhat is it, really?
An FX option gives the right — not the obligation — to exchange one currency for another at a fixed rate before or at a set date. Every FX option is two-faced by nature: a call on euros is a put on dollars; buying the right to sell dollars cheap is the same as buying the right to buy euros cheap.
The classic user is a company bidding on a foreign contract: it might win $50M of revenue in three months — or might not. A forward would lock a hedge on money it may never receive; an option hedges the maybe: pay a premium now, exercise only if the bid wins and the rate moved against them.
Macro traders love FX options for a different reason: they're the cleanest way to bet on turbulence or calm in a currency, not just direction.
Point at a line to pick it out from the others.
a paymentonly if a condition is met
Exercise is not automatic and not open-ended: it belongs to a cut-off time on the expiry date, after which the option is gone.
Two days after the trade
- The buyer → The bank Paid once. It is the most the buyer can lose, and it is why an option hedge leaves the upside intact where a forward does not.
At the cut-off on expiry
- The buyer → The bank A decision, made by a stated hour in a stated city. Miss the cut-off and an in-the-money option can simply lapse.
Two days after that
- The buyer → The bank What follows an exercise is an ordinary spot trade, settling on its own cycle.
- The bank → The buyer Delivered at the strike rate. On a cash-settled option only the difference is paid instead.
- Asset class
- FX derivatives
- Instrument type
- Option (call/put on a pair)
- Traded
- OTC (deep interbank market)
- Typical users
- Corporates, macro funds, dealers
Which risks decide the outcome
Not how risky this is, and not a rating — there is deliberately no total. It says which of five failure modes drives what happens here, in the same order on all 129 products so they can be compared. This publication's own reading; see the notice below.
- Marketdecides it
- Creditmatters
- Liquiditybarely applies
- Fundingbarely applies
- Operationaldecides it
What decides it here. The premium is the whole downside for a buyer. The operational catch is the exercise cut-off: miss the hour and an in-the-money option simply lapses.
3 · IntermediateHow it works in practice
How the FX options market talks
The interbank market quotes not prices but implied volatilities, and organises them in a peculiar, elegant grid per tenor:
- ATM vol: the at-the-money volatility level.
- Risk reversal (RR): vol of 25-delta call minus 25-delta put — the smile's tilt. A EUR/USD RR "for dollar calls" says crashes are feared in one direction.
- Butterfly (BF): how much the wings sit above ATM — the smile's curvature, i.e. the price of tail events.
Three numbers per tenor reconstruct the whole smile — a convention unique to FX.
Delta conventions
Strikes are referenced by delta (25d, 10d), not currency levels — and whether delta is spot/forward, premium-adjusted or not, differs by pair. Real desks live and die by getting the convention right.
Structures corporates actually buy
- Collars/risk reversals: buy protection, sell away some upside — cheap or zero-cost.
- Participating forwards: full protection, keep half the upside.
- Straddles/strangles: the volatility trades around elections and central-bank meetings.
4 · AdvancedPricing & valuation
Garman–Kohlhagen
Black–Scholes with the foreign interest rate as a "dividend yield" — a call on the base currency:
What the symbols mean
- Cthe price of a call option
- Sthe price of the underlying today
- rthe interest rate, per year
- Tmaturity, in years
- Nthe normal distribution, or a count
- Kthe strike: the price written into the contract
Domestic-foreign symmetry: a EURUSD call priced in USD equals the corresponding USD put priced in EUR, converted — a consistency check that catches convention bugs.
Smile construction and models
From ATM/RR/BF quotes per tenor, desks build the smile (SVI/vanna-volga/parametric), then a full surface. For exotics, calibrated dynamics matter: local vol underprices barrier/one-touch structures, stochastic vol (Heston) overshoots elsewhere — local-stochastic vol (LSV) mixtures tuned to vanillas and one-touch quotes are the FX-desk standard, because the market for touch products is liquid enough to discipline the model.
Vanna and volga
FX desks manage second-order smile Greeks explicitly: vanna (∂delta/∂vol) and volga (∂vega/∂vol) — the vanna-volga method prices simple exotics off the cost of hedging exactly these with RR and BF instruments.
What the surface reveals
Risk reversals are among macro's best sentiment gauges: EM pairs show persistent skew toward devaluation; pegged pairs price regime break as a far-wing hump. Breeden–Litzenberger on the smile yields full risk-neutral densities — event probabilities readable before referendums and elections.
The formulas above are standard textbook formulations, simplified for teaching. They explain the mechanism — they are not a valuation tool, and they will not reproduce a dealer’s price.
5 · Desk notesHow practitioners think about it
Now say it back
Close the page and give FX Option in four sentences. It takes a minute and it is the only way to find out whether reading it was enough.
- Who wants what — two parties wanted opposite things badly enough to write it down.
- What the contract obliges, and when — not the payoff; the obligation.
- Where the money comes from — name the source, or you have described a hope.
- What makes it lose — the ordinary way, not the dramatic one.
Put FX Option beside any other instrument →
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