Perfect bidder collusion through bribe and request

Abstract

We study collusion in a second price auction with two bidders in a dynamic environment. One bidder can make a take-it-or-leave-it collusion proposal, which consists of both an offer and a request of bribes, to the opponent. We show there always exists a robust equilibrium in which the collusion success probability is one. In the equilibrium, the interim expected payoff of the collusion initiator Pareto dominates the counterpart in any robust equilibria of the single-option model (Esö and Schummer ( 2004)) and any other separating equilibria in our model.