On the implied volatility of Asian options under stochastic volatility models

TL;DR

This paper analyzes the short-time implied volatility behavior of arithmetic Asian options under stochastic volatility models, deriving asymptotic formulas and validating them with numerical simulations.

Contribution

It provides a novel asymptotic analysis of implied volatility skew for Asian options in stochastic volatility settings, including rough models.

Findings

Asymptotic formula for implied volatility at short maturities

Explicit dependence of skew on volatility roughness

Numerical validation of theoretical results

Abstract

In this paper we study the short-time behavior of the at-the-money implied volatility for arithmetic Asian options with fixed strike price. The asset price is assumed to follow the Black-Scholes model with a general stochastic volatility process. Using techniques of the Malliavin calculus such as the anticipating Ito's formula we first compute the level of the implied volatility of the option when the maturity converges to zero. Then, we find and short maturity asymptotic formula for the skew of the implied volatility that depends on the roughness of the volatility model. We apply our general results to the SABR model and the rough Bergomi model, and provide some numerical simulations that confirm the accurateness of the asymptotic formula for the skew.