Mechanism choice and the buy-it-now auction: A structural model of competing buyers and sellers

- This paper studies sales mechanisms on online sales platforms like eBay.
- The model incorporates competition between buyers as well as between sellers.
- It is estimated using data from sales of baseball tickets on eBay.
- I investigate how the existence of buy-it-now auctions changes welfare.
- Buyers are better off and sellers are worse off when buy-it-now auctions exist.

A striking feature of many online sales platforms is the coexistence of multiple sales mechanisms. Items on eBay, for instance, are frequently offered through auctions, posted prices, and buy-it-now auctions. In this article, I study how this mechanism multiplicity influences the welfare of buyers and sellers. I specify and estimate a structural model of mechanism choice in online markets, in which I consider both sides of the market: On the demand side, buyers' choices among available listings are equilibrium outcomes of an entry game. On the supply side, sellers make equilibrium decisions when choosing sales mechanisms and prices. I estimate this model using data from sales of baseball tickets on eBay and calculate consumer and seller rents in three markets: the actual market with all three sales mechanisms and two counterfactual markets with auctions and fixed prices or only fixed-price listings, respectively. I find that the addition of auctions to fixed-price markets hurts sellers and risk-averse buyers but benefits risk-neutral buyers. Additionally, the consumer surplus increases when buy-it-now auctions are offered but the seller surplus is reduced further. I discuss the intuition for the cause of this result.