A Simple Model of Expert and Non-Expert Bidding in First-Price Auctions

This paper studies the equilibrium bidding behavior in a first-price sealed-bid auction when the number of informed bidders is not common knowledge. Both the independent private values and the common value cases are analyzed, under the assumption that a “neutral” signal exists. In equilibrium, experts and non-experts draw their bids from distinct supports: experts bid in the upper and lower tail of the bidding distribution and non-experts randomize their bids in between. For common values, it is shown that the seller's expected revenue always decreases with the probability of a bidder being informed when this probability is small. The opposite result is shown for the case of independent private values.Journal of Economic LiteratureClassification Numbers: D44, D82.