Too much waste, not enough rationing:the failure of stochastic, competitive markets

There are good reasons why sellers often post prices before the realization of demand shocks. We study whether equilibrium prices chosen ex ante coincide with the ex-ante prices that maximize expected aggregate surplus. The main result is that even in the competitive limit there is a divergence. Waste is excessive and entry decisions are distorted. The problem is that for competitive firms to sell in low-demand states involves a costly sacrifice of high-state revenue.