Thus, the net volatility calculated above is, in fact, the implied volatility of this synthetic forward option. While it may seem counter-intuitive that one can create a synthetic option whose implied volatility is lower than the implied volatilities of its components, consider that the first implied volatility, 18.1%, corresponds to the period from today to May expiration, while the second implied volatility, 14.3% corresponds to the period from today to September expiration. Therefore, the implied volatility for the period May to September must be less than 14.3% to compensate for the higher implied volatility during the period to May.