We consider local martingales of exponential form or , where X denotes one component of a multivariate affine process. We give a weak sufficient criterion for M to be a true martingale. As a first application, we derive a simple sufficient condition for absolute continuity of the laws of two...

Given a Markovian Brownian martingale Z, we build a process X which is a martingale in its own filtration and satisfies X1=Z1. We call X a dynamic bridge, because its terminal value Z1 is not known in advance. We compute its semimartingale decomposition explicitly under both its own filtration...

We consider the problem of maximizing the expected logarithmic utility from consumption or terminal wealth in a general semimartingale market model. The solution is given explicitly in terms of the semimartingale characteristics of the securities price process.

COGARCH is an extension of the GARCH time series concept to continuous time, which has been suggested by Klüppelberg, Lindner and Maller [C. Klüppelberg, A. Lindner, R. Maller, A continuous-time GARCH process driven by a Lévy process: Stationarity and second order behaviour, Journal of...

A small investor provides liquidity at the best bid and ask prices of a limit order market. For small spreads and frequent orders of other market participants, we explicitly determine the investor’s optimal policy and welfare. In doing so, we allow for general dynamics of the mid price, the...

We consider local martingales of exponential form or where X denotes one component of a multivariate affine process in the sense of Duffie et al. (2003) [8]. By completing the characterization of conservative affine processes in [8, Section 9], we provide deterministic necessary and...