document: Buy-it-now or take-a-chance : a simple sequential screening mechanism We present a simple auction mechanism which extends the second-price auction with reserve and is truthful in expectation . This mechanism is particularly effective in private value environments where the distribution of valuations are irregular . Bidders can `` buy-it-now '' , or alternatively `` take-a-chance '' where the top d bidders are equally likely to win . The randomized take-a-chance allocation incentivizes high valuation bidders to buy-it-now . We show that for a large class of valuations , this mechanism achieves similar allocations and revenues as Myerson 's optimal mechanism , and outperforms the second-price auction with reserve . In addition , we present an evaluation of bid data from Microsoft 's AdECN platform . We find the valuations are irregular , and counterfactual experiments suggest our BIN-TAC mechanism would improve revenue by 11 % relative to an optimal second-price mechanism with reserve .
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