A contract with multiple agents may be susceptible to collusion. We show that agents’ collusion imposes no cost in a large class of circumstances with risk neutral agents, including both uncorrelated and correlated types. In those circumstances, any payoff the principal can attain in the absence of collusion, including the secondbest level, can be attained in the presence of collusion in a way ...

This paper explores the effects that collusion can have in newspaper markets where firms compete for advertising as well as for readership. We compare three modes of competition: i) competition in the advertising and the reader market, ii) semi-collusion over advertising (with competition in the reader market), and iii) (full) collusion in both the advertising and the reader market. We find tha...

In this paper we address the question of collusion in mechanisms under asymmetric information by assuming that one of the colluding parties offers a side contract to the other one. We develop a methodology to analyze collusion as an informed principal problem. We show that if collusion occurs after the agents accept or reject the principal’s offer, the dominant-strategy implementation of the op...

We analyze a principal-supervisor-two agent hierarchy with supervisory efforts, provide a characterization of the equilibrium of the game, and show which regime improves efficiency between the collusion-proof regime and the lateral collusion one, under the assumptions that the principal is less informed, and that the side-trade is costly. By coping with the trade-off between the value of inform...

Online rating systems are subject to malicious behaviors mainly by posting unfair rating scores. Users may try to individually or collaboratively promote or demote a product. Collaborating unfair rating ’collusion’ is more damaging than individual unfair rating. Although collusion detection in general has been widely studied, identifying collusion groups in online rating systems is less studied...

We investigate the effects of bid improvement rules and bidder value asymmetry on bidder collusion in experimental ascending price auctions without communication. We find that the strict bid improvement rule and private values are not always sufficient to break collusion among well-motivated bidders. Collusion still occurs as long as bidder gains from collusion are high. JEL classification code...

0

Collusion is the practice of two or more parties deliberately cooperating to the detriment of others. While such behavior may be desirable in certain circumstances, in many it is considered dishonest and unfair. If agents otherwise hold strictly to the established rules, though, collusion can be challenging to police. In this paper, we introduce an automatic method for collusion detection in se...

On the Stability of Research Joint Ventures: Implications for Collusion * by Jo Seldeslachts, Tomaso Duso and Enrico Pennings Though there is a body of theoretical literature on research joint venture (RJV) participation facilitating collusion, empirical tests are rare. Even more so, there are few empirical tests on the general theme of collusion. This note tries to fill this gap by assuming a ...