Collusion Under Imperfect Monitoring with Asymmetric Firms

We explore the effects of asymmetries in capacity constraints on collusion where market demand is uncertain and where firms’ sales and prices are private information. We show that all firms can infer when at least one firm's sales are below some firm‐specific ‘trigger level.’ When firms use this public information to monitor the collusive agreement, price wars may occur on the equilibrium path. Symmetry facilitates collusion but, if price wars are sufficiently long, then the optimal collusive prices of symmetric capacity distributions are lower on average than the competitive prices of asymmetric capacity distributions. We draw conclusions for merger policy.     

Cartel pricing dynamics with cost variability and endogenous buyer detection

This paper characterizes collusive pricing patterns when buyers may detect the presence of a cartel. Buyers are assumed to become suspicious when observed prices are anomalous. We find that the cartel price path is comprised of two phases. During the transitional phase, price is generally rising and relatively unresponsive to cost shocks. During the stationary phase, price responds to cost but is much less sensitive than under non-collusion or simple monopoly; a low price variance may then be a collusive marker. Compared to when firms do not collude, cost shocks take a longer time to pass-through to price.     

Fine-Tailored for the Cartel-Favoritism in Procurement

In this paper, we investigate the interaction between two firms, which are involved in a repeated procurement relationship modeled as a multiple criteria auction, and an auctioneer (a government employee) who has discretion in devising the selection criteria. Our main result is that favoritism substantially facilitates collusion. It increases the gains from collusion and contributes to solving basic implementation problems for a cartel of bidders operating in a stochastically changing environment. A most simple allocation rule where firms take turns in winning, independently of stochastic social preferences and firms’ costs, achieves full cartel efficiency (including price, production, and design efficiency). In each period the selection criteria is fine-tailored to the in-turn winner: the “environment” adapts to the cartel. This result holds true when the expected punishment is a fixed cost. When the cost varies with the magnitude of the distortion of the selection criteria (compared to the true social preferences), favoritism only partially shelters the cartel from the environment. We thus find that favoritism generally facilitates collusion at a high cost for society. Our analysis suggests some anti-corruption measures that could be effective in curbing favoritism and collusion in public markets. It also suggests that the much-advocated rotation of officials is likely to be counter-productive.     

Collusion between two-sided platforms

We study the price and welfare effects of collusion between two-sided platforms and show that they depend on whether collusion occurs on both sides or a single side of the market, and whether users single-home or multi-home. Our most striking result is that one-sided collusion leads to lower (resp. higher) prices on the collusive (resp. competitive) side if the cross-group externalities exerted on the collusive side are positive and sufficiently strong. One-sided collusion may, therefore, benefit the users on the collusive side and harm the users on the competitive side. Our findings have implications regarding cartel detection and damages actions.     

ENDOGENOUS COSTS AND PRICE‐COST MARGINS: AN APPLICATION TO THE EUROPEAN AIRLINE INDUSTRY*

This paper allows for endogenous costs in the estimation of price cost margins. In particular, we estimate price‐cost margins when firms bargain over wages. We extent the standard two‐equation set‐up (demand and first‐order condition in the product market) to include a third equation, which is derived from bargaining over wages. In this way, price‐cost margins are determined by wages and vice versa. We implement the model using data for eight European airlines from 1976–1994, and show that the treatment of endogenous costs has important implications for the measurement of price‐cost margins and the assessment of market power. Our main result is that observed prices in Europe are virtually identical to monopoly prices, even though observed margins are consistent with Nash behavior. Apparently, costs had been inflated to the point that the European consumers were faced with a de facto monopoly prices.     

Yardstick Competition, Franchise Bidding and Firms’ Incentives to Collude

Collusion seems to be a pervasive problem when regional monopoly rights are auctioned to private firms. This leads us to study whether firms may collude if the regulator uses yardstick competition to simulate competitive forces, and how collusion is affected when both schemes are used. Using an infinitely repeated game framework, we find that collusion is sustainable when firms are sufficiently patient under yardstick competition. An additional franchise bidding mechanism can even help firms sustain collusion when they are impatient. When temporary monopoly rights are assigned for sufficiently long periods of time, collusion may not be sustainable even when firms are patient.     

Post-cartel tacit collusion: Determinants,consequences, and prevention

We experimentally investigate the determinants of post-cartel tacit collusion (PCTC), the effects of PCTC on market outcomes, and potential policy measures aimed at its prevention. PCTC occurs robustly with or without fines or leniency and is determined both by collusive price hysteresis and learning about cartel partners’ characteristics and strategies. As a result, it is also strongly related to the preceding cartel success. PCTC generates a downward bias in the estimated cartel overcharges. This threatens the effectiveness of deterrence induced by private damage litigation and fines imposed on colluding firms based on the overcharge. This bias further increases with preceding cartel stability such that especially more stable sets of colluding firms may be deterred less when PCTC is present. Rematching colluding subjects with strangers within a session prevents PCTC. This indicates that barring colluding managers from their posts could help impede PCTC in the field.     

Cartel sustainability in retail markets: Evidence from a health service sector

This paper studies the role of cost asymmetries and product differentiation on cartel sustainability by drawing data from a failed retail cartel. Unlike the extensive theoretical literature, little empirical evidence exists on these relationships. First, we analyze cartel compliance and find that players are more likely to comply when cost is symmetric and own cost is high. Next, based on a structural model and counterfactual experiments, we show that a cartel price that satisfies all cartel members does not exist. This result indicates an inherent difficulty of sustaining collusion in retail markets with heterogeneous players. We also show that firm heterogeneities, especially product differentiation rather than cost asymmetries, hinder collusion more. Finally, we derive the level of patience (or the discount factor) required for cartel sustainability when firms split profits based on the Shapley value.     

Symbiotic production: The case of telecommunication pricing

In this paper we analyze a generalization of vertical monopolies in which monopoly suppliers trade essential inputs with one another. The most obvious applications of the model, which we call symbiotic production, are to postal and telecommunications services. We show how producers can use per-unit tariffs to achieve cooperative outcomes without colluding directly over consumer prices. We then show the firms have an incentive to collude in the setting of tariffs but that suchcollusion will lower consumer prices. This assumes that the suppliers are otherwise unfettered. In contrast, if the constituent monopolies are regulated, we show that collusion enables the firms to completely undo the restraints of regulation. The model has important policy implications for the international telecommunications market.     

Examining models of collusion: The market for lysine

We compare the experience with collusion in the market for lysine with the predictions of theory. The lysine market provides an ideal setting following the confessions of cartel participants in antitrust investigations. Data availability allows demand and cost functions to be estimated and observed mark-ups compared with predictions. We find that several integral aspects of collusion in the lysine market are not adequately addressed in the literature: the dynamics associated with entry and investment; persistent asymmetries between firms; the cartel's bargaining problem; and the existence of cheating in equilibrium. These issues are likely to have much wider applicability beyond the lysine market.     

Speculative storage in imperfectly competitive markets

Markets for many commodities are characterized by imperfectly competitive production as well as substantial storage by speculators who are attracted by significant price volatility. We examine how speculative storage affects the behavior of an oligopoly producing a commodity for which demand is subject to random shocks. Speculators compete with consumers when purchasing the commodity and then subsequently compete with producers when selling their stocks, resulting in two opposing incentives: on the one hand, producers would like to increase production to capture future sales in advance by selling to speculators; while on the other hand, they would like to withhold production to deter speculation, thereby eliminating the additional supply from speculators in future periods. We find that the incentive to sell to speculators can be quite strong, potentially resulting in prices sufficiently high to drive consumers from the market. Furthermore, these incentives are non-monotonic in the number of producers: speculative storage occurs more frequently in a relatively concentrated oligopoly than in the extremes of monopoly or perfect competition.     

ALTERNATING MONOPOLY AND TACIT COLLUSION*

This paper considers the use of the alternating monopoly strategy (AMS) as a (tacit) collusion device. We show that firms may choose this strategy in particular environments, when other collusive strategies are also feasible. In particular, we stress how the presence of an observable move (entry), distinct from the competitive stage (price setting), can serve as a coordination device, reducing monitoring costs in incomplete information environments. The paper thus shows that AMS may be preferable to the classic market sharing strategy (MSS) and in some cases it is the only collusive equilibrium.     

Information and two-sided platform profits

We study the effect of different levels of information on two-sided platform profits—under monopoly and competition. One side (developers) is always informed about all prices and therefore forms responsive expectations. In contrast, we allow the other side (users) to be uninformed about prices charged to developers and to hold passive expectations. We show that platforms with more market power (monopoly) prefer facing more informed users. In contrast, platforms with less market power (i.e., facing more intense competition) have the opposite preference: they derive higher profits when users are less informed. The main reason is that price information leads user expectations to be more responsive and therefore amplifies the effect of price reductions. Platforms with more market power benefit because higher responsiveness leads to demand increases, which they are able to capture fully. Competing platforms are affected negatively because more information intensifies price competition.     

An oligopoly model of ocean liner shipping

In this paper I develop a simultaneous equations oligopoly model of the regulated international ocean liner shipping industry. The firms act as a cartel to determine price jointly and then set their own quality levels to maximize individual profits. The cartel does not attain monopoly profits, because each conference member myopically determines quality without regard for overall cartel profits. The results indicate that an increase in the number of firms in the cartel will increase both cartel price and quality level. An increase in price will also lead to an increase in quality level.I would like to thank Professors Alamarin Phillips, Robert Summers, and Bruce Allen for their helpful comments on earlier research for my dissertation in the Economics Department of the University of Pennsylvania on which this work is based. I am especially grateful to Professor Lawrence J. White for his encouragement and valuable suggestions at various stages of my work.     

Horizontal concentration and anticompetitive behavior in the central Canadian cement industry: testing arbitrage cost hypotheses

Consider a market with a small number of firms attempting to collude. If they successfully act as a dominant firm, they will raise price. This in turn will expand output by any fringe firms and thus reduce the market share of the colluding group. Thus, higher prices will decrease concentration over time. Here we test this hypothesis, using a modification of Spiller and Huang (1986) and data from the post-1974 Toronto cement market. The weight of the evidence indicates that market price has a negative effect on concentration, implying that the firms in this market act, with significant though limited, success as a cartel.     

The Effect of Bid Rigging on Prices: A Study of the Highway Construction Industry

This paper examines the effect of multimarket contact in afirst price sealed bid government procurement auction market. It investigates whether bidprices in the highway construction industry are related to conditions that favor the formation of a cartel.Repeated contacts among firms are found to have a significantly positive effect on the winning low bidwhich leads to higher profit. Further, rivalry among few firms tends to exacerbate the multimarket effect.The results in this study additionally support the recent theoretical predictions that collusion isbetter sustainable during economic downturns.     

Stable heterogeneous cartels

We define a nation of cartel stability which allows firms to perceive the impact of their actions on overall competitiveness in the market. We demonstrate that in an industry with linear demand and diverse linearly increasing marginal cost functions a stable cartel always exists. Furthermore, we examine uniqueness and size of such cartels as well as the impact of cost and demand conditions on their characteristics. In particular, we establish that the most efficient firms will be in the cartel while the less efficient ones will remain outside.     

Optimal cartel trigger strategies and the number of firms

Recent empirical papers have analyzed collusion in the Joint Executive Committee in an attempt to determine which of several theories of cartel behavior is supported by the behavior of this 19th century railroad cartel. Non-parametric tests of whether high and low profit regimes followed a first-order Markov process when one controls for the number of firms support the theory of optimal collusion given by Abreu, Pearce, and Stachetti. Results on whether transition probabilities depend on the number of firms are inconclusive.     

On Antitrust Enforcement and the Deterrence of Collusive Behaviour

This paper examines an antitrust enforcement policy of using significant price changes in an industry as a sorting mechanism for the allocation of resources devoted to policing collusion. That is, in either responding to complaints or initiating investigations on their own, I examine the issue of whether an antitrust enforcement policy of inferring possible collusion from significant prices changes is effective in deterring collusion given that antitrust officials have no direct knowledge of the costs of individual firms. Using the imperfect information repeated game of Green and Porter (1984), I show that this investigation strategy if coupled with uniform costs being borne by firms, can reduce the expected profits from the collusive agreement: however, unless the punishment is large enough, it will be ineffective in reducing the frequency of collusion. More importantly, it can have the undesirable effect of reducing the output agreed to by firms, if firms choose quantities, or raise collusive prices if firms are choosing price. Moreover, if the enforcement policy is anticipated by firms, the punishment mechanism adopted to support collusion will be altered to offset the policy.     

Cartelization Through Buyer Groups

Retailers may enjoy stable cartel rents in their output market through the formation of a buyer group in their input market. A buyer group allows retailers to commit credibly to increased input prices, which serve to reduce combined final output to the monopoly level; increased input costs are then refunded from suppliers to retailers through slotting allowances or rebates. The stability of such an ‘implied cartel’ depends on the retailers’ incentives to source their inputs secretly from a supplier outside of the buyer group arrangement at lower input prices. Cheating is limited if retailers sign exclusive dealing or minimum purchase provisions. We discuss the relevancy of our findings for antitrust policy.