We present first different measures of the financial market volatility, historical, instantaneous and implied in option prices. Next we analyse the long run relationship between volatility and return on financial assets. Last we examine the possible causes of volatility and its instability, that appear to be more related to the real sector of the economy than to financial innovation such as alternative investment and hedge funds.
AFTALION, F. and PONCET, P. (2004). La volatilité. Bankers, Markets and Investors, pp. 50-56.