The paper studies the robust maximization of utility from terminal wealth in a diffusion financial market model. The underlying model consists of a tradable risky asset whose price is described by a diffusion process with misspecified trend and volatility coefficients, and a non-tradable asset with a known parameter. The robust functional is defined in terms of a utility function. An explicit characterization of the solution is given via the solution of the Hamilton-Jacobi-Bellman-Isaacs (HJBI) equation.

In this paper, we consider the mean-variance hedging problem of contingent claims in a financial market model composed of assets with uncertain price parameters. We consider the worst case of model parameters required to solve the minimax problem. In general, such minimax problems cannot be changed to maximin problems. The main approach we develop is the randomization of the parameters, which allows us to change minimax to maximin problems, which are easier to solve. We provide an explicit solution for the robust mean-variance hedging problem in the single-period model for some types of contingent claims.