Jim Gatheral

Jim Gatheral spent over two decades at Merrill Lynch as a Managing Director in the equity derivatives group before transitioning to academia, where he became a Presidential Professor of Mathematics at Baruch College, City University of New York. During his time in industry he developed deep expertise in stochastic volatility modelling, local volatility, and the calibration of vol surfaces to market prices. His book "The Volatility Surface: A Practitioner's Guide" (2006) became the definitive reference text for practitioners working in equity derivatives, covering the SABR model, Heston model, SVI parameterisation, and forward variance dynamics in a unified framework accessible to both theorists and traders. The SVI (Stochastic Volatility Inspired) parameterisation he developed provides a tractable analytical framework for fitting implied volatility smiles and is widely used by derivatives desks globally. More recently, Gatheral has collaborated with Thibault Jaisson and Mathieu Rosenbaum on rough volatility models — stochastic volatility models driven by fractional Brownian motion — which have attracted significant theoretical and empirical interest for their ability to capture the roughness of volatility paths observed in market data. His academic work on market microstructure, optimal execution, and transaction cost modelling has also been widely cited.