“Second Best Efficiency in Auctions” with A.Hernando-Veciana, Submitted
We characterize the incentive compatible allocation that maximizes the expected social surplus in a single-unit sale when the efficient allocation is not implementable. This allocation may involve no selling when it is efficient to sell.  We then show that the English auction always implements the second best allocation when there are only two bidders, but not with more than two. Our model employs a unidimensional type space with independent types and allocative externalities, but captures some features of models with multidimensional types.


“Hiding Information in Open Auctions”
The defining characteristic of an open format is that it allows to aggregate extra information on top of the one that is available ex-ante. This paper shows that bidders may have an incentive to strategically manipulate this extra flow of information by employing jump bids. We show that jump bidding can have a dramatic impact on equilibrium behavior and affect revenues and efficiency in an ambiguous manner. Contrary to the common belief that jump bids are anti-competitive, it may also result in higher revenues and efficiency.

“Pre-emptive Bidding and Information acquisition”

We study an auction setting with two bidders one of whom is better informed regarding the realization of a common value component of the object on sale. The bidder with the ex-ante coarser information  can become as well informed as the initially advantaged bidder, but at a cost. We analyze the incentives to place a pre-emptive bid that discourages information acquisition and show how such incentives vary with the relative size of the common component  and on whether the informed bidder knows how her value decomposes into a private and a common value part or not. We also evaluate the effects of a jump bid on the auction's revenue and efficiency.