This paper considers the efficiency of a contestable natural monopoly if consumers are heterogeneous and the monopolist can differentiate prices imperfectly. With restricted entry, the standard result in this case is that the monopoly offers a menu of price-quantity combinations which leads to...

Oliver Hart and Bengt Holmström were awarded the 2016 Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel for their fundamental contributions to contract theory. This article offers a short summary and discussion of their path breaking work.

I study the optimal audit mechanism when the principal cannot commit to an audit strategy. Invoking a relevation principle, the agent reports her type to a mediator whi assigns contracts and recommends the principla whether to audit. For each reported type the mediator randomizes over a...