An equilibrium analysis of information aggregation and fluctuations in markets with discrete decisions

This paper shows how the interaction between decentralized information gathering and discreteness of investment decisions at the individual level can generate random fluctuations in aggregate investment that involve occasionally large allocation errors. This interaction is illustrated in a model in which private information is costly to acquire and prices reveal information. The unique rational expectations equilibrium outcome of the model is shown to always be noisy and characterized by investment levels which may be high simply because uninformed investors are buying under the impression that the high price is a signal of good investment opportunities. Moreover, the equilibrium exhibits an interesting tradeoff between the size and the frequency of aggregate allocative errors, whereby as the cost of gathering information declines the size of allocative errors increases while their occurrence decreases.