Before revision:  Third, we introduce the possibility of short-selling ; then the resale option for agents with short positions partly compensates the resale option for long agents. We characterize the unique equilibrium of our model through a Hamilton-Jacobi-Bellman equation of a novel form and use it to derive several comparative statics results .
After revision:  Third, we introduce the possibility of short-selling . A Hamilton-Jacobi-Bellman equation of a novel form and use it to derive several comparative statics results .