Dynamics and Efficiency in Decentralized Online Auction Markets

Economic theory suggests that decentralized markets can achieve efficient outcomes if buyers and sellers have many opportunities to trade. We examine this idea empirically by developing a tractable dynamic model of bidding in an overlapping, sequential auction environment and estimating the model with detailed data from eBay. Bidders in the model discount their bids to reflect the option value of losing – if they lose, they can come back to try again – and the structure of the model makes it so they effectively bid against a stationary distribution of rivals. We find that dynamic participation makes the market meaningfully more efficient than a benchmark in which buyers have only one opportunity to bid, but the observed outcomes still fall well short of the fully efficient competitive equilibrium.