Collusion in auctions and the role of communication to sustain it: a microeconomic approach

Editor’s note: This post is part of a series showcasing Barcelona GSE master projects by students in the Class of 2014. The project is a required component of every master program.

Collusion in auctions and the role of communication to sustain it: a microeconomic approach


Giuseppe Leonello

Master Program:

Competition and Market Regulation

Paper Abstract:

Collusion among bidders in auctions is an important topic in competition economics since it decreases the seller’s revenues and the social welfare. In this project the focus will be on the role of communication among bidders for the incentives to collude.

In the literature, communication among bidders has always been treated as an exogenous variable. This assumption will be relaxed and the choice of communicate will be endogenous and function of the expected collusive profits and the expected costs of collusion represented by the risk to be catch and punished.

The auctioneer can monitor the market and the auction process to discover the collusive agreement, exerting a costly effort.

The model will find the minimum level of effort needed to make bidders not having incentives to communicate and collude. However, the auctioneer will exert this level of effort only when the expected gains are higher than expected costs. For this reason, in some case the optimal choice for the auctioneer will be to lead bidders to collude even if this will not maximize the social welfare.

Government interventions to reach the not collusive equilibrium will be discussed. In particular, they will take the form of an increase in the punishment when bidders are discovered to collude and the subsidization of the cost needed to exert the optimal level of effort.

Competition and the Hold-Up Problem – Guillem Roig ’08

Editor’s note: The following post was written by Barcelona GSE alumnus Guillem Roig (Competition and Market Regulation ’08). Guillem is currently a PhD student at the Toulouse School of Economics in France.

Competition and the Hold-Up Problem: a Setting with Non-exclusive Contracts


The paper

Why some of us do not spend the desired time and resources to nurture and improve the relationship with our parents, friends or business partners? Because once the time and resources are spent, we are afraid of possible opportunistic behavior. Economists frame opportunistic behavior in simple trading relationships where a buyer and seller are able to undertake specific investment into the exchanged good. Fisher Body, a manufacturer of body cars, refused to locate their body plants adjacent to General Motors assembly plans, a move that was necessary for production efficiency.

To fight opportunistic behavior we cannot rely on “good faith” alone, but we need to establish institutions to reduce its occurrence. Many modern societies have written laws, neutral courts of justice and arranged reasonable rules to resolve disputes. Yet, what happens when a sound and solid institutional system does not exists? In this paper, I consider situations where investment contracts cannot be enforced and I explore how the introduction of competition among the sellers of an homogeneous good gives the right incentives to undertake profitable specific investment.

In these types of models, the equilibrium payoff of the sellers is a measure of their indispensability, which directly depends on the outside option available to the buyer. The trading partners invest efficiently only when the trading outcome is the most competitive. When competition is the most severe, investments do not effect the outside option of the buyer and each seller appropriates his marginal contribution of the trading surplus. Any other equilibrium gives the seller incentives to over-invest. Sellers’ investments not only generate larger trading surpluses but also reduce the outside option of the buyer. The asymmetric partition of the trading surplus generates investment inefficiencies.

In a related article, I study how the configuration of the market structure is affected by the way an endogenous number of suppliers compete in the market. With non-exclusive trade and a common buyer undertaking cooperative investment, I obtain a direct link between the level of competition and investment that affects the market structure of the supply side of the market. Trading outcomes that are more competitive are associated with a larger and more homogeneous distribution of investment among active suppliers, and an equilibrium with no investment might occur in trading outcomes that are less competitive. Buyer’s investment works as a mechanism to incentivize competition and this becomes more effective the more competitive the trading outcome is. The paper gives a theoretical insight for the coexistence of first with second tier suppliers and predicts situations where investment does not materialize.

Download the full working paper [pdf]

The process

I started this project in September 2012, after a short visit at the University of Arizona where I meet a group of law academics working on the design of trading contracts. I soon became interested in topics of contract theory and organization design and researched in the area of transaction cost economics.

The upturn of the project came in May 2013 when I benefited from an ENTER exchange program at the Universitat Autònoma de Barcelona. I presented my work in a series of seminars and the suggestions of Prof. Inés Macho and David Pérez Castrillo were invaluable at that stage of the project. I dismissed the design of complex trading contracts and I went back to basics. I concentrated on framing the problem of transaction costs without any established formal institution.

In my model, I never talk about investment contingent contracts or contract enforceability, I only allow for the interaction of economic agents in the market. In many situations, we might not need a complex and sophisticated institutional framework but we just must allow “the invisible hand” to function.

Toulouse School of Economics
Toulouse School of Economics

The working paper series of the Toulouse School of Economics are free and accessible online, so for further information please check out my articles here!

Multimarket Contact and Collusion in the Ecuadorian Pharmaceutical Sector – Master Projects 2014

Editor’s note: This post is part of a series showcasing Barcelona GSE master projects by students in the Class of 2014. The project is a required component of every master program.


Multimarket Contact and Collusion in the Ecuadorian Pharmaceutical Sector


Jerónimo Callejas and Igne Grazyte

Master Program:

Competition and Market Regulation

Paper Abstract:

The paper analyses the effects of multimarket contact on prices in the Ecuadorian pharmaceutical sector and its capacity to serve as a tool to facilitate collusion. We estimate the effect that the multimarket contact has on firms’ price setting behaviour by applying multimarket contact models and simple econometric techniques. Our findings show that multimarket contact has a positive effect on multivitamin prices in Ecuador and could indeed be helping to sustain collusion between firms.


We have tried to estimate the possible effect that multimarket contacts might have on prices and collusion in the Ecuadorian pharmaceutical industry. For the purposes of this paper we have chosen to limit our analysis and only focus on the market for multivitamins defined at the 4th ATC level. To test our predictions we tried to replicate simple techniques used by Ciliberto and Williams (2013), Evans and Kessides (1994) and Coronado (2010). We have constructed a multimarket contact index and estimated its effect on prices by using IV and then Panel Data with fixed effects estimations and also correcting for endogeneity.

As seen in section 5, our model gives robust results and provides a reasonable confirmation of our expectations: the coefficients predicted by the two models (IV and panel data with fixed effects) have the correct sings and are highly significant. Our results show that the IV estimation alone is insufficient to successfully solve all endogeneity issues, however we find that using panel data with fixed effects and also instrumenting endogenous variables (MMC) we can successfully remove the endogeneity problem from the proposed regression and obtain unbiased estimates. Our analysis shows that average multimarket contact index has a significant positive effect on price, thus confirming our predictions that the contacts between firms in different product markets can lead to higher prices for pharmaceutical products. Although we believe that this result could be indicative of possible collusive practices in the sector, the actual existence of collusion could only be confirmed by direct evidence, such as direct contacts between firms with the aim of setting prices or sharing markets.

Due to time constraints we were only able to conduct our analysis in one market and using only simple estimations and models of multimarket contact index. Therefore possible future extensions to this paper could include estimating the effect of the multimarket contact index in other markets, possibly taking into account both private and public markets; or to estimate the effect of multimarket contact by using more complex models, such as nested logit model used in Ciliberto and Williams (2013).

Read the full paper or view slides below: