Minimal Entropy Martingale Measure Research Articles

A note on convergence of option prices and their Greeks for Lévy models

We study the robustness of option prices to model variation after a change of measure where the measure depends on the model choice. We consider geometric Lévy models in which the infinite activity of the small jumps is approximated by a scaled Brownian motion. For the Esscher transform, the minimal entropy martingale measure, the minimal martingale measure and the mean variance martingale measure, we show that the option prices and their corresponding deltas converge as the scaling of the Brownian motion part tends to zero. We give some examples illustrating our results.

Malliavin Calculus Method for Asymptotic Expansion of Dual Control Problems

We develop a technique based on Malliavin--Bismut calculus ideas, for asymptotic expansion of dual control problems arising in connection with exponential indifference valuation of claims, and with minimization of relative entropy, in incomplete markets. The problems involve optimization of a functional of Brownian paths on Wiener space, with the paths perturbed by a drift involving the control. In addition there is a penalty term in which the control features quadratically. The drift perturbation is interpreted as a measure change using the Girsanov theorem, leading to a form of the integration-by-parts formula in which a directional derivative on Wiener space is computed. This allows for asymptotic analysis of the control problem. Applications to incomplete Ito process markets are given, in which indifference prices are approximated in the low risk aversion limit. We also give an application to identifying the minimal entropy martingale measure as a perturbation to the minimal martingale measure in stoc...

The minimal entropy martingale measure of a jump process influenced by jump times

In this article, we consider the problem of the minimal entropy martingale measure of a jump process influenced by jump times. The minimal entropy martingale measure of the price process is given out by the exponential martingale method, and the expression of the corresponding relative entropy is also obtained.

THE MINIMAL κ-ENTROPY MARTINGALE MEASURE

We introduce the notion of κ-entropy (κ ∈ ℝ, |κ| ≤ 1), starting from Kaniadakis' (2001, 2002, 2005) one-parameter deformation of the ordinary exponential function. The κ-entropy is in duality with a new class of utility functions which are close to the exponential utility functions, for small values of wealth, and to the power law utility functions, for large values of wealth. We give conditions on the existence and on the equivalence to the basic measure of the minimal κ-entropy martingale measure. Moreover, we provide characterizations of its density as a κ-exponential function. We show that the minimal κ-entropy martingale measure is closely related to both the standard entropy martingale measure and the well known q-optimal martingale measures. We finally establish the convergence of the minimal κ-entropy martingale measure to the minimal entropy martingale measure as κ tends to 0.

Optimal martingale measures for defaultable assets

We model a defaultable asset as solution to a stochastic differential equation driven by both a Brownian motion and the counting process martingale associated to the one-jump process. We discuss in this framework the minimal entropy martingale measure as well as the linear Esscher and the minimal martingale measure. In particular we deal with some rather delicate verification issues.

Pricing and managing risks of European-style options in a Markovian regime-switching binomial model

We discuss the pricing and risk management problems of standard European-style options in a Markovian regime-switching binomial model. Due to the presence of an additional source of uncertainty described by a Markov chain, the market is incomplete, so the no-arbitrage condition is not sufficient to fix a unique pricing kernel, hence, a unique option price. Using the minimal entropy martingale measure, we determine a pricing kernel. We examine numerically the performance of a simple hedging strategy by investigating the terminal distribution of hedging errors and the associated risk measures such as Value at Risk and Expected Shortfall. The impacts of the frequency of re-balancing the hedging portfolio and the transition probabilities of the modulating Markov chain on the quality of hedging are also discussed.

A note on utility based pricing and asymptotic risk diversification

In principle, liabilities combining both insurancial risks (e.g. mortality/longevity, crop yield,...) and pure financial risks cannot be priced neither by applying the usual actuarial principles of diversification, nor by arbitrage-free replication arguments. Still, it has been often proposed in the literature to combine these two approaches by suggesting to hedge a pure financial payoff computed by taking the mean under the historical/objective probability measure on the part of the risk that can be diversified. Not surprisingly, simple examples show that this approach is typically inconsistent for risk adverse agents. We show that it can nevertheless be recovered asymptotically if we consider a sequence of agents whose absolute risk aversions go to zero and if the number of sold claims goes to infinity simultaneously. This follows from a general convergence result on utility indifference prices which is valid for both complete and incomplete financial markets. In particular, if the underlying financial market is complete, the limit price corresponds to the hedging cost of the mean payoff. If the financial market is incomplete but the agents behave asymptotically as exponential utility maximizers with vanishing risk aversion, we show that the utility indifference price converges to the expectation of the discounted payoff under the minimal entropy martingale measure.

Option Pricing with Discrete Time Jump Processes

In this paper we propose new option pricing models based on two classes of discrete Levy-type processes. By combining these Levy processes with several volatility dynamics of the GARCH type, we aim to take into account the dynamics of financial returns in a realistic way. The associated risk neutral dynamics of the time series models is obtained through two different specifications for the pricing kernel: we provide a characterization of the change in the probability measure using the Esscher transform and the Minimal Entropy Martingale Measure. We finally assess empirically the performance of this modelling approach, using a dataset of European options based on the CAC 40. Our empirical findings show that discrete time Levy based models behave well regardless of the volatility dynamics and of the pricing kernel. A different specification is however required to obtain the best results for options with a shorter or longer maturity.

Semi-Markov regime switching interest rate models and minimal entropy measure

In this paper, we present a discrete time regime switching binomial-like model of the term structure where the regime switches are governed by a discrete time semi-Markov process. We model the evolution of the prices of zero-coupon when given an initial term structure as in the model by Ho and Lee that we aim to extend. We discuss and derive conditions for the model to be arbitrage free and relate this to the notion of martingale measure. We explicitly show that due to the extra source of uncertainty coming from the underlying semi-Markov process, there are an infinite number of equivalent martingale measures. The notion of path independence is also studied in some detail, especially in the presence of regime switches. We deal with the market incompleteness by giving an explicit characterization of the minimal entropy martingale measure. We give an application to the pricing of a European bond option both in a Markov and semi-Markov framework. Finally, we draw some conclusions.

The density process of the minimal entropy martingale measure in a stochastic volatility market. A PDE Approach

In a stochastic volatility market the Radon-Nikodym density of the minimal entropy martingale measure can be expressed in terms of the solution of a semilinear partial differential equation (PDE). This fact has been explored and illustrated for the time-homogeneous case in a recent paper by Benth and Karlsen [3]. However, there are some cases which time-dependent parameters are required such as when it comes to calibration. This paper generalizes their model to the time-inhomogeneous case.

The Minimal Entropy Martingale Measure (MEMM) for a Markov-Modulated Exponential Lévy Model

This paper deals with the characterization problem of the minimal entropy martingale measure (MEMM) for a Markov-modulated exponential Levy model. This model is characterized by the presence of a background process modulating the risky asset price movements between different regimes or market environments. This allows to stress the strong dependence of financial assets price with structural changes in the market conditions. Our main results are obtained from the key idea of working conditionally on the modulator-factor process. This reduces the problem to studying the simpler case of processes with independent increments. Our work generalizes some previous works in the literature dealing with either the exponential Levy case or the exponential-additive case.

Asymptotic utility-based pricing and hedging for exponential utility

Abstract This paper deals with pricing and hedging based on utility indifference for exponential utility. We consider the limit for vanishing risk aversion or, equivalently, small quantities of the contingent claim. In first order approximation the utility indifference price and the corresponding hedge can be determined from the corresponding quadratic hedging problem relative to the minimal entropy martingale measure. This extends similar results obtained by Mania and Schweizer [21], Becherer [3], and Kramkov and Sîrbu [20,19].

Optimal Exponential Utility in a Jump Bond Market

We consider the optimal exponential utility in a bond market with jumps basing on a model similar to Björk et al. [4], which is arbitrage free. Similar to the normalized integral with respect to the cylindrical martingale first introduced in Mikulevicius and Rozovskii [13], we introduce the (𝕄, Q 0)-normalized martingale and local (𝕄, Q 0)-normalized martingale. For a given maturity T 0 ∈ [0, T*], we describe the minimal entropy martingale (MEM) based on [T 0, T*] by a backward semimartingale equation (BSE) w.r.t. the (𝕄, Q 0)-normalized martingale. Then we give an explicit form of the optimal approximate wealth to the optimal exp-utility problem by making use of the solution of the BSE. Finally, we describe the dynamics of the exp utility indifference valuation of a bounded contingent claim H ∈ L ∞(ℱ T 0 ) by another BSE under the minimal entropy martingale measure in the incomplete market.

The Minimal Entropy Martingale Measure (MEMM) for a Markov-Modulated Lévy Model

This paper deals with the characterization problem of the minimal entropy martingale measure (MEMM) for a Markov-modulated exponential Levy model. This model is characterized by the presence of a factor modulating the risky asset price movements between different regimes. We circumvent the difficulty caused by the modulator factor by using the special properties of Markov additive process. Our work generalizes some previous works in the literature which have treated either the exponential Levy case or the exponential-additive case.

An Equilibrium Approach to Indifference Pricing

The utility indifference framework has received a lot of attention, because it is based on a utility maximization principle, which is one of the most fundamental principles of economics, for pricing a contingent claim. The price based on utility indifference framework is the maximum or minimum (in some cases, threshold) price for each investor. Therefore, the price is the indicator for the investor to join the market of the contingent claim. Our purpose is to expand the view of utility indifference framework, that is, to deduce the equilibrium price in the utility indifference framework. We attain the result that, under the setting of exponential utility, the equilibrium price will be uniquely evaluated by minimal entropy martingale measure.

RISK-NEUTRAL MEASURES AND PRICING FOR A PURE JUMP PRICE PROCESS

This article considers the asset price movements in a financial market when risky asset prices are modeled by marked point processes. Their dynamics depend on an underlying event arrivals process, modeled again by a marked point process. Taking into account the presence of catastrophic events, the possibility of common jump times between the risky asset price process and the arrivals process is allowed. By setting and solving a suitable control problem, the characterization of the minimal entropy martingale measure is obtained. In a particular case, a pricing problem is also discussed.

Option pricing in bilateral Gamma stock models

Abstract In the framework of bilateral Gamma stock models we seek for adequate option pricing measures, which have an economic interpretation and allow numerical calculations of option prices. Our investigations encompass Esscher transforms, minimal entropy martingale measures, p-optimal martingale measures, bilateral Esscher transforms and the minimal martingale measure. We illustrate our theory by a numerical example.

The Minimal Entropy Martingale Measure and Numerical Option Pricing for the Barndorff–Nielsen–Shephard Stochastic Volatility Model

We develop and apply a numerical scheme for pricing options in the stochastic volatility model proposed by Barndorff–Nielsen and Shephard. This non-Gaussian Ornstein–Uhlenbeck type of volatility model gives rise to an incomplete market, and we consider the option prices under the minimal entropy martingale measure. To numerically price options with respect to this risk neutral measure, one needs to consider a Black and Scholes type of partial differential equation, with an integro-term arising from the volatility process. We suggest finite difference schemes to solve this parabolic integro-partial differential equation, and derive appropriate boundary conditions for the finite difference method. As an application of our algorithm, we consider price deviations from the Black and Scholes formula for call options, and the implications of the stochastic volatility on the shape of the volatility smile.

Evaluation of the MEMM, Parameter Estimation and Option Pricing for Geometric Lévy Processes

In this paper, we shall propose a useful approach to evaluate concretely the MEMM (minimal entropy martingale measure) for the typical geometric Levy processes such as compound Poisson, stable, VG (Variance Gamma), CGMY (Carr-Geman-Madan-Yor), NIG (Normal Inverse Gaussian), etc. In addition, we shall estimate the parameters of geometric Levy processes and value the European call option and Asian call option using the Nikkei financial data.

Utility-based hedging and pricing with a nontraded asset for jump processes

Optimal strategies for hedging a claim on a nontraded asset X are analyzed. The claim is valued and hedged in an exponential utility maximization frame using a correlated traded asset S . The traded asset is described as a geometric jump process and the nontraded asset as a jump-diffusion process having common jump times with S . The classical dynamic programming approach leads to characterizing the value function as a solution to the Hamilton–Jacobi–Bellman equation. Closed form formulas for the value function, in terms of a new probability measure Q ∗ equivalent to the real world probability measure P , and for the optimal investment strategy are given. Admissibility for the optimal strategy is discussed and, via a duality result, an explicit expression for the density of the minimal entropy martingale measure (MEMM) is provided. Closed form formulas are also given for the writer’s indifference price in terms of Q ∗ and the MEMM.