We experimentally compare collusive behaviors in first-price sealed-bid auctions without and with a reserve price. Before the auction begins, a bidder may offer a bribe to the other bidder, in exchange for a commitment not to participate in the auction. We find that the average offer and the rate of successful bribes are significantly lower in the treatment with a reserve price. These results are largely due to responding bidders who demand a greater share of the benefit from collusion. Although imposing a reserve price reduces efficiency, its optimality and bribe deterrence shift the surplus from the bidders to the seller.
