In this paper we give a financial justification, based on non arbitrage conditions,of the (H) hypothesis in default time modelling. We also show how the (H) hypothesis isaffected by an equivalent change of probability measure.[...]

This paper develops a default-risky bond pricing model, which assumes that the default intensity is driven by a Markov chain and which accounts for default and liquidity risk. A representation of the bond price dynamics, which separates three different types of risk, was obtained. Introducing...

This paper studies in some examples the role of information in a default-risk framework. In a first-passage model, we assume that investors obtain two types of information about the firm’s unlevered asset value at a discrete sequence of dates. The effects of information on the distributional...

We consider backward stochastic dierential equations (BSDEs) witha particular quadratic generator and study the behaviour of their solu-tions when the probability measure is changed, the ltration is shrunk,or the underlying probability space is transformed.[...]

We study the exponential utility indifference valuation of a contingentclaim H when asset prices are given by a general semimartingale S. Under mildassumptions on H and S, we prove that a no-arbitrage type condition is fulfilled ifand only if H has a certain representation. In this case, the...

We introduce and study no-good-deal valuation bounds defined in terms of expected utility. A utility-based good deal is a payoff whose expected utility is toohigh in comparison to the utility of its price. Forbidding good deals induces, viaduality, restrictions on pricing kernels and thereby...

We study the exponential utility indifference valuation of a contingent claim B in an incomplete market driven by two Brownian motions. The claim depends on a nontradable asset stochastically correlated with the traded asset available for hedging. We use martingale arguments to provide upper and...

This paper studies modelling and existence issues for market models of option prices in a continuous-time framework with one stock, one bond and a family of European call options for one fixed maturity and all strikes. After arguing that (classical) implied volatilities are ill-suited for...

This paper studies modelling and existence issues for market models of stochastic implied volatility in a continuous-time framework with one stock, one bank account and a family of European options for all maturities with a fixed payoff function h. We first characterize absence of arbitrage in...

A generalized correlated random walk is a process X_k of partial sums of random variables Y_j such that (X,Y) forms a Markov chain. For a sequence X^n of such processes where each Y^n_j takes only two values, we prove weak convergence to a diffusion process whose generator is explicitly...