양면시장의 정의 및 조건

초록

The traditional theories in industrial organization economics such as inverse elasticity pricing rule, price discrimination may not applied or should be modified when we deal with two-sided markets. This comes from the special characteristic of two-sided markets especially cross network externality between two different groups of consumers (or suppliers). For the same reason, the traditional market definition methods, market power evaluation, criteria for anti-competitive behaviors should be modified in two-sided markets. Thus if we use the traditional theories without modification when we consider issues of two-sided market, there is possibility to commit type I or type II errors. For example, the pricing under marginal cost of dominant firm is regarded as predatory pricing in one-sided market. But in two-sided market it is not anti-competitive predatory pricing but just profit maximization behavior. Therefore it is very important to clarify whether the market is one-sided or two-sided(or multi-sided). However the structure of market is just treated as a given condition when we construct a theoretical model. But in the real world, market is not a given condition but an object to be defined. But until now there is no clear definition and criteria to decide whether the market is two-sided or not. The only academic definition is the Rochet & Tirole (2004)'s definition. And the most popular conditions of two-sided market is Evans (2003), and Evans & Schmalensee (2008)'s condition. But the condition is only necessary condition for two-sided market. Thus this paper tries to introduce more clear definition and decision criteria of two-sided markets. We introduce axioms of no-side-payment, cross network externality etc to define two-sided market. And we introduce an algorithm to decide whether a market is two-sided or not.

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