In finance, volatility arbitrage (or vol arb) is a term for financial arbitrage techniques directly dependent and based on volatility.
A common type of vol arb is type of statistical arbitrage that is implemented by trading a delta neutral portfolio of an option and its underlying. The objective is to take advantage of differences between the implied volatility[1] of the option, and a forecast of future realized volatility of the option's underlying. In volatility arbitrage, volatility rather than price is used as the unit of relative measure, i.e. traders attempt to buy volatility when it is low and sell volatility when it is high.[2][3]