Risk-Sinsitive Dynamic Portfolio Optimization with Partial Information on Infinite Time Horizon

We consider an optimal investment problem for a factor model treated by Bielecki and Pliska (Appl. Math. Optim. 39 337.360) as a risk-sensitive stochastic control problem, where the mean returns of individual securities are explicitly affected by economic factors defined as Gaussian processes. We relax the measurability condition assumed as Bielecki and Pliska for the investment strategies to select. Our investment strategies are supposed to be chosen without using information of factor processes but by using only past information of security prices. Then our problem is formulated as a kind of stochastic control problem with partial information. The case on a finite time horizon is discussed by Nagai (Stochastics in Finite and Infinite Dimension 321.340. Birkhäuser, Boston). Here we discuss the problem on infinite time horizon.