두 가지 거래형태에서의 수직적 결합에 대한 분석

초록

There have been many literatures which analyze the effect of vertical integration in the market withvertical structure. Vertical integration has two effects: efficiency effect and strategic effect. First, verticalintegration allows a firm not only to reduce transaction cost but also to experience on-time productionand makes quality control or product differentiation easier. Firms may be less flexible, however, as thesize of the firm gets bigger, and less efficient due to the secure demand or supply. There are two kinds of strategic effect: double marginalization and externality effect. When transactionoccurs between independent firms, each firm will impose a mark-up, thus a price will be higher, which iscalled double marginalization. There are two types of externality effects: vertical and horizontal. Externality effect arises when a firm's behavior affects the other firm, but the former does not take thisinto consideration when it makes a decision. If this happens between a upstream and downstream firm, itis vertical externality effect, and double marginalizaion is one example. Horizontal externality effectswhich arise between either upstream or downstream firms affect prices, quality and promotion level. Tosolve these externality problems, not only vertical integration but also vertical restraints such as resaleprice maintenance, exclusive territory or exclusive dealings can be used. McGuire and Staelin analyze the effect of vertical integration when the upstream firm supplies itsproduct through one exclusive downstream firm. They find that product substitutability affects theequilibrium distribution structure in a market with two differentiated upstream firms and two identicaldownstream firms. For low degrees of substitutability, each upstream firm will integrate vertically. Forhigh degrees of substitutability, they will be more likely not to integrate. Moorthy claims that McGuire and Staelin's finding depends on the following two factors: the degree ofsubtitutability between product and strategic complements. First, decentralization cannot be a Nashequlibrium unless unilateral decentralization raises the other upstream firm's equilibrium retail pricewhen the upstream firms' products are substitutes. Second, unilateral decentralization always raises hisown equilibrium consumer price, but whether it raises or lowers the rival's consumer price depends onwhether there are strategic complements or not. He finds that the decentralized downstream firm'sconsumer price increases because of a higher marginal cost due to double marginalization. Further, withdecentralization, the rival downstream firm's price also increases in case of strategic complements. Withhigh degree of substitutability, the second effect dominates, thus firms are not integrated. In this paper, I analyze the effect of vertical integration in a successive duopoly market where upstreamfirms are vertically and downstream firms are horizontally differentiated. As in McGuire and Staelin, Ifound that there are two symmetric Nash equilibria where upstream firms can be either verticallyintegrated or separated, and the latter is dominant in that profits are higher. This results comes from twocountervailing effects of vertical integration. First, a firm's price gets lower because of lack of double marginalization. But, this price cut makes the rival's price lower with strategic complementarity. In fact,the price cut for the integrated firm is higher than for the rival. When the rival firm is not verticallyintegrated, the price cut of the integrated firm is not large enough for it to make sufficiently more sales,thus a higher profit. Meanwhile, when the rival firm is vertically integrated, the price cut is so large that itcan earn a higher profit. I also deal with the case where both upstream firms can supply to both downstream firms. When theself-selection condition is satisfied, consumers with high preference buy high-quality goods and thosewith low preference buy low-quality goods. Wholesale prices are decided to satisfy self-selectionconstraints. The degree of vertical differentiation does not affect consumer prices, but the degree ofhorizontal differentiation does. As a result, both upstream firms will be integrated as the profit increasesas much as the profit of a decentralized downstream firms.

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