Kristin Reikvam () (Department of Mathematics, University of Oslo, P.O. Box 1053, Blindern, N-0316 Oslo, Norway and MaPhySto - Centre for Mathematical Physics and Stochastics, University of Aarhus, Ny Munkegade, DK-8000 Å rhus, Denmark http://www.math.uio.no/fredb/) Fred Espen Benth () (Department of Mathematics, University of Oslo, P.O. Box 1053, Blindern, N-0316 Oslo, Norway and MaPhySto - Centre for Mathematical Physics and Stochastics, University of Aarhus, Ny Munkegade, DK-8000 Å rhus, Denmark http://www.math.uio.no/fredb/) Kenneth Hvistendahl Karlsen () (Department of Mathematics, University of Bergen, Johs. Brunsgt. 12, N-5008 Bergen, Norway http://www.mi.uib.no/~kennethk/ Manuscript)
Abstract
We consider an optimal portfolio-consumption problem which incorporates the notions of durability and intertemporal substitution. The logreturns of the uncertain assets are not necessarily normally distributed. The natural models then involve Lévy processes as driving noise instead of the more frequently used Brownian motion. The optimization problem is a singular stochastic control problem and the associated Hamilton-Jacobi-Bellman equation is a nonlinear second order degenerate elliptic integro-differential equation subject to gradient and state constraints. For utility functions of HARA type, we calculate the optimal investment and consumption policies together with an explicit expression for the value function when the Lévy process has only negative jumps. For the classical Merton problem, which is a special case of our optimization problem, we provide explicit policies for general Lévy processes having both positive and negative jumps. Instead of following the classical approach of using a verification theorem, we validate our solution candidates within a viscosity solution framework. To this end, the value function of our singular control problem is characterized as the unique constrained viscosity solution of the Hamilton-Jacobi-Bellman equation in the case of general utilities and general Lévy processes.
Download Info
To download:
If you experience problems downloading a file, check if you have the
proper application to
view it first. Information about this may be contained
in the File-Format links below. In case of further problems read
the IDEAS help
page. Note that these files are not on the IDEAS
site. Please be patient as the files may be large.
As the access to this document is restricted, you may want to look for a different version under "Related research" (further below) or search for a different version of it.