  We consider the problem of optimal portfolio selection under forward
investment performance criteria in an incomplete market. The dynamics of the
prices of the traded assets depend on a pair of stochastic factors, namely, a
slow factor (e.g. a macroeconomic indicator) and a fast factor (e.g. stochastic
volatility). We analyze the associated forward performance SPDE and provide
explicit formulae for the leading order and first order correction terms for
the forward investment process and the optimal feedback portfolios. They both
depend on the investor's initial preferences and the dynamically changing
investment opportunities. The leading order terms resemble their time-monotone
counterparts, but with the appropriate stochastic time changes resulting from
averaging phenomena. The first-order terms compile the reaction of the investor
to both the changes in the market input and his recent performance. Our
analysis is based on an expansion of the underlying ill-posed HJB equation, and
it is justified by means of an appropriate remainder estimate.
