Information revelation in auctions

Auction theory has emphasized the importance of private information to the profits of bidders. However, the theory has failed to consider to what extent initially private information will remain private. We show that in a variety of contexts bidders will reveal their information, even if this information revelation is (ex ante) detrimental to them. Similarly, a seller may reveal her information although this revelation lowers revenues. We also show that bidders may be harmed by private information, even in contexts where more information has traditionally been presumed to be beneficial.