ABSTRACT
It is traditional in antitrust policy to distinguish between the restrictive business practice, or cartel, dimension and the industrial concentration aspect. In the former otherwise independent firms acquire an influence on the market by virtue of a concertation of behaviour. By contrast the concentration problem emphasizes the point that individual firms may in their own right possess or come to possess a degree of market power. The most obvious phenomenon under the concentration heading is monopoly. It should however be emphasized that a true monopolist is not as common as the use of the word monopoly might suggest. The reasons for this are that the conditions for the existence of such a market position are quite rigorous. There must be only one supplier of a good and there must be no close substitutes to which consumers can switch if the monopolist chooses to raise his price.
