Perfect bidder collusion through bribe and request

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 that there always exists a robust equilibrium in which the collusion success probability is one. In the equilibrium, for each type of initiator the expected payoff is generally higher than the counterpart in any robust equilibria of the single-option model (Es\"{o} and Schummer (2004)) and any other separating equilibria in our model

Commitment in First-Price Auctions

We study a variation of the single-item sealed-bid first-price auction where one bidder (the leader) is given the option to publicly pre-commit to a distribution from which her bid will be drawn

Simple collusive agreements in one-shot first-price auctions

The paper demonstrates that collusion in a private value first price auction is likely to occur even in a one shot interaction. The strategies of the colluding parties must be mixed since agreeing to submit a bid equal to the reservation price of the seller provides the incentive for that bidder to cheat on the designated winner. We deal with a complete information environment with arbitrary number of bidders. We characterize the sensible equilibrium outcome where the two bidders with the highest valuations collude. We show that the equilibrium outcome is unique and that the probability of collusion exceeds 1/2.