“…Lévy processes [7,8,9,10], stochastic volatility models [11,12,13,6,14,15] or cumulant expansions around the Black-Scholes case [16,17,18,19,10] constitute approaches which have been successful in capturing some of the features of real option prices. For example the recent 'stochastic alpha, beta, rho' (SABR) model ( [6], and see Appendix C) can be well-fit to empirical skew surfaces.…”