We offer a new explanation of equilibrium rationing. As is well known, a monopolist selling a durable good and not able to commit to a price sequence has an incentive to lower the price once the consumers with the greatest willingness to pay have bought, but this induces consumers to postpone...

It is here shown that there exist cost innovations for which a monopolist has a higher incentive to invest than a social planner. This unveils the limits of the claim, based on Arrow (1959), that a monopoly always has a lower incentive to innovate than a social planner and therefore than...