ARSENAL > Volatility smile

Volatility smile

Theory
Definition
The pattern that out-of-the-money options trade at higher implied volatilities than at-the-money options. Empirical violation of Black-Scholes (which assumes constant vol).

Equity smiles are typically asymmetric ("smirk" or "skew") — OTM puts pricier than OTM calls because crash risk is asymmetric. FX smiles are more symmetric. Drives sophisticated derivatives pricing models (SABR, Heston).
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