Interlinkage and Generous Tit‐for‐Tat Strategy

We investigate an infinitely‐repeated prisoners' dilemma with imperfect monitoring and consider the possibility that the interlinkage of the players' distinct activities enhances implicit collusion. We show a necessary and sufficient condition for the existence of a generous tit‐for‐tat Nash equilibrium. Such an equilibrium, if it exists, is unique. This equilibrium achieves approximate efficiency when monitoring is almost perfect, where the discount factors are fixed.     

Tacit collusion in repeated auctions

This paper considers the question of tacit collusion in repeated auctions with independent private values and with limited public monitoring. McAfee and McMillan show that the extent of collusion is tied to the availability of transfers. Monetary transfers allow cartels to extract full surplus. A folk theorem proved by Fudenberg et al. (Econometrica 62 (1994) 997-1039) shows that transfers of future payoffs are almost as good if players are patient and communicate before auctions. We ask how the scope of collusion is affected if players dispense with explicit communication and their monitoring is limited. Collusion better than bid rotation is still feasible, but full surplus cannot be extracted. This constraint becomes less severe with more players and large cartels can become asymptotically efficient even with very limited monitoring.     

Trade Liberalization and Cartel Stability

Can reduced trade barriers promote a collusive understanding about not exporting into each others domestic markets? Reduced trade costs increase the short‐run gains from starting exporting, but can also make the long‐run punishment of such a strategy harsher. If collusion on prices is supported by a trigger strategy, a reduction in trade costs weakens competition in the sense that collusion is easier to sustain. In a corresponding model with collusion on quantities, this conclusion is reversed. The authors also discuss how results change if grim trigger strategies are replaced by stick‐and‐carrot punishments.     

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.     

Efficient collusion in repeated auctions with communication

This paper studies collusion in repeated auctions when bidders communicate prior to each stage auction. For independent and correlated private signals and general interdependent values, the paper identifies conditions under which an equilibrium collusion scheme is fully efficient in the sense that the bidders’ payoff is close to what they get when the object is allocated to the highest valuation bidder at the reserve price in every period.     

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.     

Collusion analysis of the Alabama liquid asphalt market

The Alabama liquid asphalt market in the USA is examined over the period 1961–1978 for evidence of activity consistent with collusion. Some 14 conditional collusion-facilitating factors that could influence a market's tendency towards collusion, not all equally important or necessarily in agreement with every other factor, were considered. While some of these factors are controversial and can help or harm a collusion, the net balance of factors and all of the important factors and evidence pointed towards being consistent with a conspiracy. While not examined as extensively, it was also found that the circumstantial evidence in the market was also consistent with collusion. This article suggests a procedural methodology for initiation and resolution of suspected collusion for determining appropriate damages. While the precise law and damages allowed will be country-specific, the general methodology should have wide application in many countries whose laws attempt to foster and preserve competition and punish and deter monopoly acquired and maintained by acting badly, such as by colluding or exclusionary conduct.     

Collusion in Dynamic Bertrand Oligopoly with Correlated Private Signals and Communication

This paper studies collusion in repeated Bertrand oligopoly when stochastic demand levels for the product of each firm are their private information and are positively correlated. It derives general sufficient conditions for efficient collusion through communication and a simple grim-trigger strategy. This analysis is then applied to a model where the demand signal has multiple random components which respond differently to price deviations. In this model, it is shown that the above sufficient conditions hold if idiosyncratic noise terms are sufficiently small. Journal of Economic Literature Classification Numbers: C72, D82.     

同质市场中产量匹配惩罚策略下的默契合谋

本文研究了同质产品市场中产量匹配惩罚策略下的默契合谋。我们得到的结论如下:(1)同质市场中的默契合谋是可能的;(2)垄断产量不可能通过合谋实现;(3)与纳什回归惩罚策略相比,合谋有可能更加困难,也有可能同等容易。我们将得到的结论与Lu and Wright(2010)所研究的价格匹配惩罚策略下的默契合谋进行了比较,并给出了一个线性需求函数的例子。     

Robustness to strategic uncertainty

We introduce a criterion for robustness to strategic uncertainty in games with continuum strategy sets. We model a player's uncertainty about another player's strategy as an atomless probability distribution over that player's strategy set. We call a strategy profile robust to strategic uncertainty if it is the limit, as uncertainty vanishes, of some sequence of strategy profiles in which every player's strategy is optimal under his or her uncertainty about the others. When payoff functions are continuous we show that our criterion is a refinement of Nash equilibrium and we also give sufficient conditions for existence of a robust strategy profile. In addition, we apply the criterion to Bertrand games with convex costs, a class of games with discontinuous payoff functions and a continuum of Nash equilibria. We show that it then selects a unique Nash equilibrium, in agreement with some recent experimental findings.     

UNIQUENESS OF EQUILIBRIUM PAYOFFS IN FINITELY REPEATED GAMES WITH IMPERFECT MONITORING*

This paper examines when a finitely repeated game with imperfect monitoring has a unique equilibrium payoff vector. This problem is nontrivial under imperfect monitoring, because uniqueness of equilibrium (outcome) in the stage game does not extend to finitely repeated games. A (correlated) equilibrium is equilibrium minimaxing if any player's equilibrium payoff is her minimax value when the other players choose a correlated action profile from the actions played in the equilibrium. The uniqueness result holds if all stage game correlated equilibria are equilibrium minimaxing and have the same payoffs. The uniqueness result does not hold under weaker conditions.     

Market power of firms and exchange-rate fluctuations

This paper explores the potential of firms to restrict industry outputs (market power) in oligopolistically organized markets where domestic firms compete with foreign ones. Within a stochastic price-setting supergame framework, market power is shown to be lower in general with flexible exchange rates for the following reasons. (i) The conditions that the fully collusive outcome—oligopolists maximizing joint profits — is sustainable in equilibrium become stronger if the exchange rate fluctuates, provided that fluctuations are sufficiently small. (ii) Even if full collusion can be sustained, industry outputs will be higher on the average with flexible than with fixed exchange rates.     

差异化产品价格战的产生与扩散机制分析

本文基于消费者的"0-1"购买特征和产品的纵向差异化特征,建立了一个新的价格战模型。通过应用数学证明和数值模拟的方法发现:(1)合谋体系、背叛体系以及价格战体系的均衡结果均与需求冲击无关;(2)差异化产品厂商的背叛动机以及产品链条的合谋稳定性也与需求冲击无关;(3)产品的差异化程度是影响合谋稳定性的重要因素,差异化程度越大,合谋越稳定;(4)合谋集团对背叛厂商的惩罚策略存在着"误伤效应",这种效应在一定条件下能够自我抑制,表现为产品链条上的价格战和合谋共存,在其他条件下,这种效应不能自我抑制,价格战一旦发动就会迅速扩散到整个产品链条。     

发展中国家普遍服务义务的经济分析

本文构建一个简单的非对称信息模型,分析发展中国家特定的普遍服务问题。在模型中,政府与垄断企业的非对称信息产生于在农村提供服务的边际成本,最优普遍服务政策可以用两种规制手段即资费和网络投资来实现。本文对区别定价和统一定价两种情形进行了对比分析,得出的结论是：在实施区别定价时,与完全信息相比,不完全信息将提高农村地区的资费水平,并且减小相应的网络覆盖面积;而在实施统一定价时,农村地区的定价可能降低,但这是以网络覆盖面积的减小为代价。模型结果还表明,合谋的成胁会弱化企业的激励。有意思的是,在这两种定价机制下,企业和纳税人这两种不同的利益集团均有同规制者合谋的动机。实际上,纳税人利益集团的存在,强化了规制者和企业之间的防止合谋约束,并且为了减少规制者同纳税人利益集团的合谋收益,即使规制者具有高成本信息,也会使配置结果扭曲。     

Collusion and Renegotiation in a Principal–Supervisor–Agent Relationship

We describe a principal–supervisor–agent relationship in which agent and supervisor may collude. To prevent collusion, the principal may contract on a noisy signal which is correlated with the occurrence of collusion. When the signal is informative enough, the principal uses it and no collusion occurs in equilibrium. These contracts, however, are ex post inefficient and are only optimal if the principal can commit not to renegotiate. With renegotiation it is never optimal for the principal to prevent collusion and, at the same time, condition contracts on the signal. In fact, when the signal is informative enough collusion occurs in equilibrium.     

Bid rotation and collusion in repeated auctions

This paper studies bidder collusion with communication in repeated auctions when no side transfer is possible. It presents a simple dynamic bid rotation scheme which coordinates bids based on communication history and enables intertemporal transfer of bidders’ payoffs. The paper derives a sufficient condition for such a dynamic scheme to be an equilibrium and characterizes the equilibrium payoffs in a general environment with affiliated signals and private or interdependent values. With IPV, it is shown that this dynamic scheme yields a strictly higher payoff to the bidders than any static collusion scheme which coordinates bids based only on the current reported signals.     

The effect of leniency programs on endogenous collusion

The objective of a leniency program is to reduce sanctions against collusion if a participant voluntarily confesses his behavior or cooperates with the public authority’s investigation. Constructing a model in which the detection probability varies over time, Harrington (2008) pointed out that there are three channels through which the leniency program can affect the collusion amount; furthermore, he presented a sufficient condition under which the maximum leniency is optimal. After extending the model by endogenizing the degree of collusion as well as equilibrium selection in the self-reporting stage, we revealed that the Race to the Courthouse effect disappears and that the maximum reduction is always optimal.     

When imperfect collusion is profitable

This paper studies cartel stability under the assumption that member firms can choose intermediate degrees of collusion as well as the joint-profit-maximizing solution in determining the quota to be produced by each firm. After showing that firms can increase the number of participants by decreasing the degree of collusion, I prove that individual members' profits are maximized when firms choose a (possibly low) degree of collusion such that all firms in the industry want to take part in the cartel. More precisely, if the number of firms in the industry is four or less, then all of them want to take part in the cartel even if the maximum degree of collusion is chosen (i.e., the monopoly output is produced); if the number of firms is greater than four, firms will still create an industry-wide cartel but they will produce a higher quantity than the monopoly output.     

Asymmetric cross-price effects and collusion

Asymmetries in cross-price elasticities have been demonstrated by several empirical studies, but received little attention by the theoretical literature. In this paper we study from a theoretical stance how introducing asymmetry in the substitution effects influences the sustainability of collusion. We first characterize the equilibrium of a linear Cournot duopoly with substitute goods, and consider substitution effects which are asymmetric in magnitude. Since the two goods are asymmetric strategic substitutes, the production decisions are driven by the firm which is relatively less influenced by the rival. We then study partial collusion using the folk theorem's solution concept. Our main result shows that the interval of quantities supporting collusion in the asymmetric setting is always smaller than the interval in the symmetric benchmark. The asymmetry in the substitution effects thus hinders collusion.     

Tacit collusion with imperfect monitoring in the Canadian manufacturing industry: an empirical study

This article undertakes a cross-sectoral analysis of a salient empirical implication of the model of tacit collusion advanced by Abreu, Pearce, and Stachetti (1986). Specifically, we assess the prevalence of a first-order Markovian process for alternating between price wars and collusive periods through nonparametric tests. The analysis focuses on 30 different industries in Canada. The evidence provides weak support for optimal collusion in one industry, which is consistent with the idea that such kind of collusive arrangements is unusual, or, if collusion is all too common, that price wars as deviations from collusion are rare.