International Journal of Theoretical and Applied Finance

Foreign-currency denominated securities are introduced in a stochastic model à la Missale [13]. It is shown that the percentage share of this bond type, as compared to total debt, is an increasing function of the covariance between the output and the rate of depreciation, but it may or may not be a decreasing function of the volatility of the rate of depreciation.

The paper introduces a new method for the estimation of time-varying regression coefficients employed in financial modeling. We use Malliavin calculus (stochastic calculus of variations) to estimate the time-varying regression coefficients that appear in linear regression models, and the generalized Clark–Ocone formula to derive a closed-form solution for the estimates of the time-varying coefficients. While this approach can be applied to any signal model, we present its application to signals modeled as a Brownian motion and an Ornstein–Uhlenbeck process. Simulation results prove the superiority of the proposed method, as compared to conventional methods.

We consider a model of margin trading based on the hyperfinite timeline. Using only elementary nonstandard analysis we are able to derive explicit formulas for the expected margin call time and loss. Further margin trading strategy is studied and an application to pricing barrier option is given. We prove a generalization of the Catalan numbers which forms the combinatoric basis of our results and should be of independent interest.

We consider the asymptotic behavior of options under stochastic volatility models for which the volatility process fluctuates on a much faster time scale than that defined by the riskless interest rate. We identify the distinguished asymptotic limits and, in contrast with previous studies, we deal with small volatility-variance (vol-vol) regimes. We derive the corresponding asymptotic formulae for option prices, and find that the first order correction displays a dependence on the hidden state and a non-diffusive terminal layer. Furthermore, this correction cannot be obtained as the small variance limit of the previous calculations. Our analysis also includes the behavior of the asymptotic expansion, when the hidden state is far from the mean. In this case, under suitable hypothesis, we show that the solution behaves as a constant volatility Black–Scholes model to all orders. In addition, we derive an asymptotic expansion for the implied volatility that is uniform in time. It turns out that the fast scale plays an important role in such uniformity. The theory thus obtained yields a more complete picture of the different asymptotics involved under stochastic volatility. It also clarifies the remarkable independence on the state of the volatility in the correction term obtained by previous authors.

In this paper, we consider a renewal risk model with dividend barrier, in which the claim inter-occurrence times are generalized exponential. We obtain explicit expression for the probability of absorption by an upper barrier b, before ruin occurs when the claim amount distribution is either mixed exponential or Gamma. We apply these results to obtain the distribution of the maximum deficit at the time of ruin. We also consider the numerical evaluation of the barrier probability, B(u, b), and the probability of maximum severity in some specific cases.

A generalized Black–Scholes–Merton economy is introduced. The economy is driven by Brownian motion in random time that is taken to be continuous and independent of Brownian motion. European options are priced by the no-arbitrage principle as conditional averages of their classical values over the random time to maturity. The prices are path dependent in general unless the time derivative of the random time is Markovian. An explicit self-financing hedging strategy is shown to replicate all European options by dynamically trading in stock, money market, and digital calls on realized variance. The notion of the average price is introduced, and the average price of the call option is shown to be greater than the corresponding Black–Scholes price for all deep in- and out-of-the-money options under appropriate sufficient conditions. The model is implemented in limit lognormal random time. The significance of its multiscaling law is explained theoretically and verified numerically to be a determining factor of the term structure of implied volatility.

In the present paper we give some preliminary results for option pricing and hedging in the framework of the Bates model based on quadratic risk minimization. We provide an explicit expression of the mean-variance hedging strategy in the martingale case and study the Minimal Martingale measure in the general case.

We hedge options on electricity spot prices by cross hedging, i.e., by using another financial asset. We calculate hedging strategies by quadratic minimization and local risk minimization. In our model of energy markets, we have done a deep study of no arbitrage and of the existence of martingale measures with square integrable density. Then we have established tools for efficient hedges. Nevertheless, we have clearly proved possible limitations of the expiry of options with quadratic criteria.