Hilary Term Lectures 5 & 6.

Multi-Firm Behaviour

Tacit Collusion

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Explicit v. Tacit Collusion

Phlips (1995)


Tacit Collusion

'In an oligopolistic situation, with its precarious internal equilibrium, there is much to be gained from simply and widely understood rules of thumb, which minimize the danger of behaviour intended to be peaceful and co-operative being misunderstood as predatory or retaliatory.'

Modigliani, F., (1958): New Developments on the Oligopoly Front, Journal of Political Economy, 66 (June): 215-32.


Concerted Practice.

Definition of concerted practice.

'….a form of co-ordination between undertakings which, without having reached the stage where an agreement properly so called has been concluded, knowingly substitutes practical co-operation between them for the risks of competition.'

Case 48/69 ICI v. Commission ('dyestuffs') [1972] ECR 619.

How Much Cooperation is Required?

In Suiker Unie ECJ held that concept of concerted practice did not require the working out of an actual plan and that:

'…each economic operator must determine independently the policy which he intends to adopt on the common market including the choice of the persons and undertakings to which he makes offers or sells…[T]his requirement …does,…, strictly preclude any direct or indirect contact between such operators…to influence the conduct on the market of an actual or potential competitor or to disclose to such competitor the course of conduct which they themselves have decided to adopt or contemplate adopting on the market.' Case 47/73, Suiker Unie v. Commission [1975] ECR 1663.

Parallel Behaviour Not Enough

Slade (1987): Interfirm Rivalry in a Repeated Game: An Empirical Test of Tacit Collusion, Journal of Industrial Economics, 35: 499-516 and reproduced in Phlips ed. Applied Industrial Economics.


Facilitating Practices

Announcing Price Changes

But Problems When Other Explanation Lacking.

The Great Salt Duopoly.

Rees (1993): Collusive Equilibrium in the Great Salt Duopoly, Economic Journal , 103: 833-48, reproduced in Phlips ed. Applied Industrial Economics

Airline Tariff Publishing Case

A final thought on information exchange.


Most Favoured Customer Clauses

Meeting Competition Clause


What Can the Law Do About Oligopoly?


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