Abstract
We conduct a laboratory experiment to study a decentralized market where players engage in multiple simultaneous trading games. We implement different trading protocols which allow players to keep all information about their evaluations and bids private, and revise their bids if they wish so. We show that protocols allowing for bargaining dramatically improve efficiency with respect to the benchmark scenario of a sealed-bid multilateral blind auction, mainly to the benefit of players rather than the silent auctioneer. This is because participants seek to reveal information through a gradual bidding-up strategy that favors bargaining environments. Aggregate efficiency nonetheless suffers from the fact that participants raise their bids gradually, buyers bargain harder than sellers, and some players over-bargain to appropriate a larger share of the unknown surplus.