“…In fact, volatility is the only parameter that needs to be estimated and we could argue that in option markets, investors trade volatility. Second, volatility measurement is an important issue for policy makers, portfolio managers and financial market participants because it can be used as a measurement of risk, providing an important input for portfolio management, option pricing and market regulation (Poon and Granger, 2003;Badescu et al, 2008). Third, a related issue, which has become very clear during the 2007-2009 financial crisis, is that greater volatility in the financial markets raises important questions about the stability of the global financial system and its consequences on the real economy.…”