Using a suitable Hull and White type formula we develop a methodology to obtain a second order approximation to the implied volatility for very short maturities. Using this approximation we accurately calibrate the full set of parameters of the Heston model. One of the reasons that makes our...

Although liquidity and informational efficiency, among others, are important characteristics of a securities market, they are not, or should not be, ends in themselves. From a normative point of view, the ultimate goal is to maximize the welfare of society. Therefore, the critical question about...