FX Volatility Modeling: Risk Reversals, Butterflies, and the Currency Vol Surface

In FX options, the difference between a usable surface and a misleading one often lies in conventions, quote translation, and model discipline. This book is written for practitioners who need to get those details right: derivatives quants, structurers, traders, risk managers, and developers working on currency options and exotics desks. It provides a desk-level guide to how FX volatility is actually quoted, transformed, calibrated, and used in pricing and risk.

The book takes the reader from option-pricing foundations into the distinct microstructure of currency volatility markets: spot and forward relationships, domestic and foreign discounting, tenor and settlement rules, and the full family of FX delta conventions, including premium adjustment and dN formulations. It then shows how ATM, risk reversal, and butterfly quotes are mapped into put and call volatilities, converted from delta space into strike space, and assembled into a continuous no-arbitrage surface. From there, the reader learns how to calibrate SABR, compare local and stochastic volatility approaches, and build robust numerical and production workflows.

A particular strength of the book is its treatment of barrier options and smile dynamics, where surface construction choices have immediate pricing and hedging consequences. The presentation is practical and implementation-oriented, with enough theory to support sound judgment but always tied back to market conventions, calibration stability, and the realities of running an FX volatility book.