We develop a dynamic theory of managerial turnover in a world in which the quality of the match between a firm and its managers changes stochastically over time. Shocks to managerial productivity are anticipated at the time of contracting but privately observed by the managers. Our key positive result shows that the firm's optimal retention decisions become more permissive with time. Our key normative result shows that, compared to what is efficient, the firm's contract induces either excessive retention at all tenure levels or excessive firing at the early stages of the relationship, followed by excessive retention after sufficiently long tenure.

We study the profit-maximizing price path of a monopolist selling a durable good to buyers who arrive over time and whose values for the good evolve stochastically. The setting is completely stationary with an infinite horizon. Contrary to the case with constant values, optimal prices fluctuate with time. We argue that consumers’ randomly changing values offer an explanation for temporary price reductions that are often observed in practice. (JEL D82)

We study the optimal dynamics of incentives for a manager whose ability to generate cash flows changes stochastically with time and is his private information. We show that distortions (aka, wedges) under optimal contracts may either increase or decrease over time. In particular, when the manager's risk aversion and ability persistence are small, distortions decrease, on average, over time. For sufficiently high degrees of risk aversion and ability persistence, instead, distortions increase, on average, with tenure. Our results follow from a novel variational approach that permits us to tackle directly the "full program," thus bypassing some of the difficulties of the "first-order approach" encountered in the dynamic mechanism design literature.

We study the optimal mechanism in a dynamic sales relationship where the buyer's arrival date is uncertain, and where his value changes stochastically over time. The buyer's arrival date is the …rst date at which contracting is feasible and is his private information. To induce immediate participation, the buyer is granted positive expected rents even if his value at arrival is the lowest possible. The buyer is punished for arriving late; i.e., he expects to earn less of the surplus. Optimal allocations for a late arriver are also further distorted below …rst-best levels. Conditions are provided under which allocations converge to the e¢ cient ones long enough after contracting, and this convergence occurs irrespective of the time the contract is initially agreed (put di¤erently, the so-called "principle of vanishing distortions" introduced by Battaglini (2005) continues to apply irrespective of the buyer's arrival date).

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