We consider an exchange economy with two heterogeneous stocks and twogroups of investors. Dividends follow diusion processes, with a constant expectedgrowth rate for one stock and a stochastic drift for the other. 'Rationalinvestors' can either observe this stochastic drift without error or...

In this paper we study the equilibrium in a heterogeneous economy with twogroups of investors. Over-confident experts incorrectly assume that their signalfor the drift of the dividend process is correlated with the true drift, butinterpret the signal otherwise perfectly. Rational laymen avoid...

Model mis-specification can cause substantial utility losses in portfolio planning.In this paper, we compare two approaches to cope with this problem,robust control and learning. We derive the optimal portfolio strategies and theutility losses due to model mis-specification. Surprisingly,...