Structure-preserving equivalent martingale measures for ℋ-SII models

In this paper we relate the set of structure-preserving equivalent martingale measures ℳsp for financial models driven by semimartingales with conditionally independent increments to a set of measurable and integrable functions 𝒴. More precisely, we prove that ℳsp ≠ ∅ if and only if 𝒴 ≠ ∅, and connect the sets ℳsp and 𝒴 to the semimartingale characteristics of the driving process. As examples we consider integrated Lévy models with independent stochastic factors and time-changed Lévy models and derive mild conditions for ℳsp ≠ ∅.

Pricing European options and risk measurement under exponential Lévy models — a practical guide

This paper provides a thorough survey of the European option pricing, with new trends in the risk measurement, under exponential Lévy models. We develop all steps of pricing from equivalent martingale measures construction to numerical valuation of the option price under these measures. We then construct an algorithm, based on Rockafellar and Uryasev representation and fast Fourier transform, to compute Risk indicators, like the VaR and the CVaR of derivatives. The results are illustrated with an example of each exponential Lévy class. The main contribution of this paper is to build a comprehensive study from the theoretical point of view to practical numerical illustration and to give a complete characterization of the studied equivalent martingale measures by discussing their similarity and their applicability in practice. Furthermore, this work proposes applications to the Fourier inversion technique in risk measurement.

ASYMPTOTIC ARBITRAGE IN THE HESTON MODEL

In this paper, we introduce a new form of asymptotic arbitrage, which we call a partial asymptotic arbitrage, half-way between those of Föllmer & Schachermayer (2007) [Mathematics and Financial Economics 1 (34), 213–249] and Kabanov & Kramkov (1998) [Finance and Stochastics 2, 143–172]. In the context of the Heston model, we establish a precise link between the set of equivalent martingale measures, the ergodicity of the underlying variance process and this partial asymptotic arbitrage. In contrast to Föllmer & Schachermayer (2007) [Mathematics and Financial Economics 1 (34), 213–249], our result does not assume a suitable condition on the stock price process to allow for (partial) asymptotic arbitrage.

Equivalent or absolutely continuous probability measures with given marginals

Let (X,A) and (Y,B) be measurable spaces. Supposewe are given a probability α on A, a probability β on B and a probability μ on the product σ-field A ⊗ B. Is there a probability ν on A⊗B, with marginals α and β, such that ν ≪ μ or ν ~ μ ? Such a ν, provided it exists, may be useful with regard to equivalent martingale measures and mass transportation. Various conditions for the existence of ν are provided, distinguishing ν ≪ μ from ν ~ μ.

ROLE OF INFORMATION IN PRICING DEFAULT-SENSITIVE CONTINGENT CLAIMS

We consider a financial market with a savings account and a stock S that follows a general diffusion. The default of the company, which issues the stock S, is modeled as a stopping time with respect to the filtration generated by the value of the firm that is not observable by regular investors. We assume that the stock price and the value of the firm are correlated. We study three investors with different information levels trading in the market who aim to price a general default-sensitive contingent claim. We use the density approach and Yor's method to solve the pricing problem. Specifically, we find the sets of equivalent martingale measures in three cases and, when needed, we choose one of them using f-divergence approach.