Abstract

“Relevant market”is a key concept in the antitrust field. Relevant mar-ket definition is a ghost in the antitrust field, a devil from which economists want to free themselves. Except for a few cases to which the per se rule ap-plies, law enforcement authorities have to define a relevant market before evaluating the anticompetitive effects in merger cases, cartel cases or market dominant position abuse cases.

The book first clears relevant theoretical issues and the research situation of relevant market. Second, the book reviews definition methods for relerant market systematically. Third, under the same settings, studies the relations a-mong SSNIP and its implementation methods in three scenarios: unknown demand function, linear demand function and constant elasticity demand func-tion. Then relaxing some hypothese: demand curves are smooth, marginal cost keeping constant in the price rise range, candidate products are substitutes of each other, investigates the consequences of relaxing them, and proposes a new way to solve the problems. Finally, we will analyze Coca - Cola/Huiyuan case and Oracle/Sun case. Through the two cases, we study practical problems during the course of defining relevant market in real cases. For exam-ple, how to define relevant market in real cases? What are the relations among many popular relevant market definition methods in real cases?

Our results show that：

（1）The choice of demand function or relevant market definition meth-od may decide the boundary of relevant market.

（2）The version of SSNIP or price increase style also has important im-pacts on relevant market definition.

（3）When there are two or more different goods in candidate market, the“can”version of SSNIP and its implementation methods is invalid. In or-der to solve this problem, we propose a new way to implement critical loss a-nalysis.

（4）If the kink of demand curve closes to origin, it may lead to cello-phane fallacy. If the kink of demand curve is away from origin, it may lead to reverse cellophane fallacy. If marginal cost increases in the range of price rise, we may define a too broad relevant market. If marginal cost decreases in price rise range, we may define a too narrow relevant market. In order to define rele-vant market correctly, we propose an approach which is based on conjecture to implement critical loss analysis.

（5）In real cases, different relevant market definition method may de-fine the same relevant market. When short of information, we need to collect information in all kinds of ways. For example, Markov matrix can tell us some demand substitute information.