We analyse a version of Spence's job market signalling model in which firms can make job offers before workers complete their education. Workers cannot commit to turning down such offers. Offers are private, so that workers are unable to use one firm's offer in an attempt to elicit better offers from other firms. In the unique sequential equilibrium outcome of the model with unproductive education, there is no wasteful education. When education is productive, the standard model predicts that more able individuals become overeducated to separate themselves from less able workers. In our model, less able workers become overeducated to (partially) pool with more able workers. The pooling mutes the incentives of high ability workers, who in consequence actually choose to become undereducated. We examine the robustness of our result to modifications to the basic model.

We consider discriminatory auctions for multiple identical units of a good. Players have private values, possibly for multiple units. None of the usual assumptions about symmetry of players' distributions over values or symmetry of equilibrium play are made. Because of this, equilibria will typically involve inefficient allocations. Equilibria also become very difficult to solve for. Using an approach which does not depend on explicit equilibrium calculations we show that such auctions become arbitrarily close to efficient as the number of players, and possibly the number of objects, grows large, and provide a simple characterization of limit equilibria.

We consider discriminatory and uniform price auctions for multiple identical units of a good. Players have private values, possibly asymmetrically distributed and for multiple units. Our setting allows for aggregate uncertainty about demand and supply. In this setting, equilibria generally will be inefficient. Despite this, we show that such auctions become arbitrarily close to efficient if they are "large, " and use this to derive an asymptotic characterization of revenue and bidding behavior.

We consider an auction in which k identical objects of unknown value are auctioned off to n bidders. The k highest bidders get an object and pay the k + 1st bid. Bidders receive a signal that provides information about the value of the object. We characterize the unique symmetric equilibrium of this auction. We then consider a sequence of auctions A r with n r bidders and k r objects. We show that price converges in probability to the true value of the object if and only if both k r → ∞ and n r - k r → ∞, i.e., both the number of objects and the number of bidders who do not receive an object go to infinity.

The tension between allocative efficiency and information aggregation is explored in the context of an auction: k identical objects of unknown quality are auctioned off to n bidders whose tastes affect their valuation of an object of given quality. Bidders receive a signal about the quality of the objects. The k highest bidders get an object and pay a price equal to the k + 1st highest bid. We find conditions under which, in the limit, objects are allocated efficiently to those with the highest tastes, and price converges in probability to the value of an object to the marginal taste type.

We consider large double auctions with private values. Values need be neither symmetric nor independent. Multiple units may be owned or desired. Participation may be stochastic. We introduce a very mild notion of “a little independence.” We prove that all nontrivial equilibria of auctions that satisfy this notion are asymptotically efficient. For any α>0, inefficiency disappears at rate 1/n2-α.

We consider the choice between stocks and options to provide effort incentives to a risk-averse manager. We show that stocks can dominate options as a means of motivation only if nonviability risk is substantial, as in financially distressed firms or start-ups. Options dominate stocks for other firms. These results hold regardless of the existing portfolio of the manager. We provide empirical evidence that higher bankruptcy risk is indeed correlated with more use of stock. The Author 2007. Published by Oxford University Press on behalf of The Society for Financial Studies. All rights reserved. For Permissions, please email: [email protected], Oxford University Press.

We show existence of equilibria in distributional strategies for a wide class of private value auctions, including the first general existence result for double auctions. The set of equilibria is invariant to the tie-breaking rule. The model incorporates multiple unit demands, all standard pricing rules, reserve prices, entry costs, and stochastic demand and supply. Valuations can be correlated and asymmetrically distributed. For double auctions, we show further that at least one equilibrium involves a positive volume of trade. The existence proof establishes new connections among existence techniques for discontinuous Bayesian games.

Different extensive form games with the same reduced normal form can have different information sets and subgames. This generates a tension between a belief in the strategic relevance of information sets and subgames and a belief in the sufficiency of the reduced normal form. We identify a property of extensive form information sets and subgames which we term strategic independence. Strategic independence is captured by the reduced normal form, and can be used to define normal form information sets and subgames. We prove a close relationship between these normal form structures and their extensive form namesakes. Using these structures, we are able to motivate and implement solution concepts corresponding to subgame perfection, sequential equilibrium, and forward induction entirely in the reduced normal form, and show close relations between their implications in the normal and extensive form.

We provide general conditions under which principal-agent problems admit mechanisms that are optimal for the principal. Our result covers as special cases those in which the agent has no private information – i.e., pure moral hazard – as well as those in which the agent’s only action is a participation decision – i.e., pure adverse selection. We allow multi-dimensional actions and signals, as well as both …nancial and non-financial rewards. Beyond measurability, we require no a priori restrictions on the space of mechanisms. Consequently, our optimal mechanisms are optimal among all measurable mechanisms. A key to obtaining our result is to permit randomized mechanisms. We also provide conditions under which randomization is unnecessary.