Lyapunov exponents of nilpotent Itô systems with random coefficients

The paper considers the top Lyapunov exponent of a two-dimensional linear stochastic differential equation. The matrix coefficients are assumed to be functions of an independent recurrent Markov process, and the system is a small perturbation of a nilpotent system. The main result gives the asymptotic behavior of the top Lyapunov exponent as the perturbation parameter tends to zero. This generalizes a result of Pinsky and Wihstutz for the constant coefficient case.