Bidder collusion

We analyze bidder collusion at first-price and second-price auctions. Our focus is on less than all-inclusive cartels and collusive mechanisms that do not rely on auction outcomes. We show that cartels that cannot control the bids of their members can eliminate all ring competition at second-price auctions, but not at first-price auctions. At first-price auctions, when the cartel cannot control members’ bids, cartel behavior involves multiple cartel bids. Cartels that can control bids of their members can suppress all ring competition at both second-price and first-price auctions; however, shill bidding reduces the profitability of collusion at first-price auctions.     

Core-stable rings in auctions with independent private values

We propose a semi-cooperative game theoretic approach to check whether a given coalition is stable in a Bayesian game with independent private values. The ex ante expected utilities of coalitions, at an incentive compatible (noncooperative) coalitional equilibrium, describe a (cooperative) partition form game. A coalition is core-stable if the core of a suitable characteristic function, derived from the partition form game, is not empty. As an application, we study collusion in auctions in which the bidders? final utility possibly depends on the winner?s identity. We show that such direct externalities offer a possible explanation for cartels? structures (not) observed in practice.     

Self-enforced collusion through comparative cheap talk in simultaneous auctions with entry

Campbell (J Econ Theory 82:425–450, 1998) develops a self-enforced collusion mechanism in simultaneous auctions based on complete comparative cheap talk and endogenous entry, with two bidders. His result is difficult to generalize to an arbitrary number of bidders, since the entry-decision stage of the game is characterized by strategic substitutes. This paper analyzes more-than-two-bidder, symmetric-prior cases. Two results are proved: (1) as the number of objects grows large, a full comparative cheap talk equilibrium exists and it yields asymptotically fully efficient collusion; and (2) there is always a partial comparative cheap talk equilibrium. All these results are supported by intuitive equilibria at the entry-decision stage (J Econ Theory 130:205–219, 2006; Math Soc Sci 2008, forthcoming). Numerical examples suggest that full comparative cheap talk equilibria are not uncommon even with few objects.     

FINITELY REPEATED PRISONERS' DILEMMA WITH SMALL FINES: THE PENANCE CONTRACT*

This paper investigates finitely repeated prisoners' dilemma games with explicit contractual devices. It shows that full collusion can be achieved in a unique manner by incentivizing the players' final‐period play with small fines. The incentivizing modality is the penance contract, by which a player is penalized if and only if he deviates from the penance strategy in the final period. Using this contractual agreement brings the penance strategy profile into unique subgame perfect equilibrium in the entire game and achieves full collusion without being invalidated by renegotiation.     

License prices for financially constrained firms

It is often alleged that high auction prices inhibit service deployment. We investigate this claim under the extreme case of financially constrained bidders. If demand is just slightly elastic, auctions maximize consumer surplus if consumer surplus is a convex function of quantity (a common assumption), or if consumer surplus is concave and the proportion of expenditure spent on deployment is greater than one over the elasticity of demand. The latter condition appears to be true for most of the large telecom auctions in the US and Europe. Thus, even if high auction prices inhibit service deployment, auctions appear to be optimal from the consumers’ point of view.      

Endogenous Cartel Formation

This paper investigates the endogenous formation of cartels in a supergame framework in which cheating on the cartel agreement results in the ejection of only the defector from the cartel while collusion continue s amongst the non-cheating members. A more sophisticated notion of cartel stability than has been analysed hitherto is developed here, and it is shown that cartels are even less stable than they are generally believed to be. When firms produce heterogeneous goods and set prices, cartels comprising a small fraction of the industry's firms are shown to be viable. The emergence of two or more cartels within the same industry is seen not only to be a distinct possibility but also to be quite likely     

Blowing the Whistle

Leniency clauses, offering cartelists legal immunity if they blow the whistle on each other, is a recent anti-trust innovation. The authorities wish to thwart cartels and promote competition. This effect is not evident, however; whistle-blowing may enforce trust and collusion by providing a tool for cartelists to punish each other. We examine the impact of leniency law, and other rules, experimentally.     

Multi-player contests with asymmetric information

We consider imperfectly discriminating, common-value, all-pay auctions (or contests) in which some players know the value of the prize, others do not. We show that if the prize is always of positive value, then all players are active in equilibrium. If the prize is of value zero with positive probability, then there is some threshold number of informed players such that if there are less, all uninformed players are active, and otherwise all uninformed players are inactive.     

R&D COOPERATION BETWEEN IMPATIENT RIVALS

We analyse R&D cooperation between product‐market competitors within a repeated‐game framework with imperfect monitoring. When firms are patient enough, R&D cooperation is attainable without product‐market collusion. However, if firms are less patient, we show that collusion in the product market is necessary to sustain R&D cooperation. Moreover, consumers can be better off when collusion is allowed in this case.     

On the genericity of full surplus extraction in mechanism design

Heifetz and Neeman [A. Heifetz, Z. Neeman, On the generic (im)possibility of full surplus extraction, Econometrica 74 (2006) 213-233], using convex combinations of models, showed that full surplus extraction (FSE) in mechanism design is generically impossible, contrary to the seminal work of Cremer and McLean [J. Cremer, R. McLean, Full extraction of the surplus in Bayesian and dominant strategy auctions, Econometrica 53 (1988) 345-361]. Since Cremer and McLean did not allow convex combinations of models, the two results are not comparable. We show that FSE is generically impossible when convex combinations of models are not allowed, provided that we do not hold fixed the cardinality of models.     

Unique Implementation of the Full Surplus Extraction Outcome in Auctions with Correlated Types

In auctions with correlated types it is possible to design mechanisms such that full surplus extraction can be obtained as the outcome of an equilibrium in which agents use (weakly) dominant strategies. However, it is not assured that the outcome is unique. We present an example in which no mechanism can yield the full surplus extraction outcome as the unique Bayesian equilibrium outcome. Next we show that in the standard auction model the multiplicity problem can be fully resolved using sequential mechanisms, i.e., we show that it is possible to obtain the full surplus extraction outcome as the unique perfect Bayesian equilibrium outcome.Journal of Economic LiteratureClassification Numbers: D44; D70.     

The formation of networks with transfers among players

We examine the formation of networks among a set of players whose payoffs depend on the structure of the network, when players may bargain by promising or demanding transfer payments when forming links. We vary three aspects of the game: (i) whether players can only make transfers to (and receive transfers from) players to whom they are directly linked, or whether they can also subsidize links that they are not directly involved in, (ii) whether or not transfers relating to a given link can be made contingent on the full resulting network or only on the link itself, and (iii) whether or not players can pay other players to refrain from forming links. We characterize the networks that are supported under these variations and show how each of the above aspects either accounts for a specific type of externality, or deals with the combinatorial nature of network payoffs.     

eBay’s proxy bidding: A license to shill

We introduce a bidding strategy which allows the seller to extract the full surplus of the high bidder in eBay auctions. We call this a “Discover-and-Stop” bidding strategy and estimate that 1.39 percent of all bids in eBay auctions are placed by sellers (or accomplices) who execute this strategy. We argue that this kind of shill bidding is unnecessarily effective due to eBay’s proxy system and the predictability of other bidders’ bids. We also model eBay auctions with shill bidding and find that, in equilibrium, eBay’s profits are higher with shilling than without it. Finally, to determine whether bidders have an incentive to bid on their own items, we mimic the bidding behavior of shill bidders in actual eBay auctions and find some evidence of the strategy’s success.     

Collusion in one-shot second-price auctions

Summary. Most of the literature on collusive behavior in auctions ignores two important issues that make collusion difficult to sustain at least in one-shot interactions: the detection of cheating and the verification of bids. Colluding bidders may deceive each other by using shill bidders. Also, if the identities of the bidders and their bids are not published then it would be difficult to verify the bid of a colluding bidder. This paper addresses these problems in one shot second price auctions where one bidder offers another bidder a side payment in exchange for not participating in the auction, while the number of other bidders is stochastic. In spite of the barriers to collusion mentioned above, a simple side payment mechanism which depends only on the auction price is introduced. It induces a successful collusion, eliminates the verification problem, provides no incentive for the use of shill bidders and guarantees that the proponent obtains ex-post non-negative payoff. The colluding bidders are ex-ante strictly better off compared with the competitive case, irrespective of their types.Received: 27 November 2002, Revised: 28 January 2005, JEL Classification Numbers: C72, D44, D82.Yair Tauman: Correspondence toWe would like to thank an anonymous referee for very valuable comments and suggestions that significantly improved the paper. We thank Shmuel Zamir for a helpful discussion.     

Trade liberalization,forward‐looking firms,and welfare

We set up an oligopolistic model with two exporting firms selling to a third market to investigate the welfare implications of trade liberalization when the exporting firms are forward‐looking. The results show that with cost asymmetry trade liberalization encourages the exporting firms to engage in tacit collusion, which may not only be detrimental to the domestic welfare, but also to the consumer surplus of the importing country. Moreover, we find that tacit collusion is less sustainable if the government of the importing country imposes a lower (higher) tariff on the more (less) efficient exporting firm. If a nonforward‐looking or a forward‐looking cost‐efficient domestic firm exists in the importing country, then trade liberalization also encourages tacit collusion.     

Collusion in mixed oligopolies and the coordinated effects of privatization

We study the sustainability of collusion in mixed oligopolies where private and public firms only differ in their objective: private firms maximize profits, while public firms maximize total surplus. If marginal costs are increasing, public firms do not supply the entire market, leaving room for private firms to produce and possibly cooperate by restricting output. The presence of public firms makes collusion among private firms harder to sustain, and maybe even unprofitable. As the number of private firms increases, collusion may become easier or harder to sustain. Privatization makes collusion easier to sustain, and is socially detrimental whenever firms are able to collude after privatization (which is always the case if they are sufficiently patient). Coordinated effects thus reverse the traditional result according to which privatization is socially desirable if there are many firms in the industry.     

Contracting with capacity constrained suppliers

This paper characterizes the optimal and efficient mechanisms to allocate simultaneously two substitute tasks to two suppliers. Two main results emerge from this analysis. First, even under some regularity conditions efficiency and optimality do not systematically coincide. Efficiency can always be achieved using some second price auctions which are optimal when both suppliers compete for the same task. When there is competition for different tasks the optimal production is distorted from efficiency over a nondegenerate interval of types so as to extract the full surplus over that interval. Second, full extraction of the surplus may still guarantee incentive compatibility. Received: November 2, 1998; revised version: March 2, 2000     

Structural holes in social networks

We consider a setting where every pair of players that undertake a transaction (e.g. exchange goods or information) creates a unit surplus. A transaction can take place only if the players involved have a connection. If the connection is direct the two players split the surplus equally, while if it is indirect then intermediate players also get an equal share of the surplus. Thus, individuals form links with others to create surplus, to gain intermediation rents, and to circumvent others who are trying to become intermediary.Our analysis clarifies the interplay between these forces in the process of strategic network formation. First, we show that, in the absence of capacity constraints on links, it leads to the emergence of a star network where a single agent acts as an intermediary for all transactions and enjoys significantly higher payoffs. Second, we study the implications of capacity constraints in the ability of agents to form links. In this case, distances between players must be long, which induces players who are “far off” to connect in order to avoid paying large intermediation rents. A cycle network then emerges, payoffs being equal across all players.     

Does a ‘non-committed’ government always generate lower social welfare than its ‘committed’ counterpart? Strategic trade policy when consumer surplus matters

We show that social welfare in the setup where the government lacks the full ability to commit to its trade policies may exceed the social welfare when the government possesses full commitment power if consumer surplus is part of the social welfare function. This is never the case in the standard, “third market” framework of strategic trade policy. We provide two examples in which consumer surplus matters: the “home market” and the “intra-industry trade” setup. The policy instruments under consideration are import tariffs and export subsidies and there are R&D spillovers from the domestic to the foreign firm.     

Collusion Without Conspiracy: An Experimental Study of One-Sided Auctions

The study investigates collusion-nonfacilitating features of one-sided auctions. We report the results of oral nondescending bid auction experiments in which the strict bid improvement rule was absent, and compare them with the results of sealed bid auction experiments. In the sealed bid experiments the outcomes converged to the competitive equilibrium. In the oral auctions, collusive outcomes emerged and were sustained with bidders using bid matching strategies. We conclude that oral auctions provide opportunities for tacit coordination and collusion enforcement that do not exist under the sealed bid. Therefore, the strict bid improvement rule becomes critical for breaking collusion.