sentences:  To see this, consider that the two options essentially offset each other from today until the expiration of the short May option.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.