購併或助併？使用互補要素的Cournot寡占市場的垂直整併分析

To Merge or to Help Related Firms Merge? Vertical Mergers in Cournot Oligopolies with Complementary Inputs

考慮一個連續寡占市場其最終財的生產需要投入兩種互補要素:一種為獨占廠商生產的必要要素，另一種為寡占廠商生產的一般要素。我們比較獨占要素廠商採取助併或購併策略的獲利表現，並發現:當上、下游相關廠商家數少時，獨占要素廠商可藉由補貼部分垂直相關廠商進行垂直結合，以誘發最大數量的成對垂直結合，並攫取消除產業雙重加價的效率利得。相對的，當上、下游相關廠商家數多時，採行助併策略所需付出的補貼成本隨之上升。此時，獨占要素廠商購併一家下游廠商並對其下游競爭廠商進行市場封鎖可獲得最大利潤。

Consider a successive oligopoly where the production of a final good requires two complementary inputs: one essential input produced by a sole supplier and one generic input produced by oligopolistic suppliers. We compare the profitability of two strategies for the essential input supplier: one is to help related firms merge vertically; the other is to acquire a downstream firm itself. We show that it is in the interest of the essential input supplier to subsidize a fraction of firms in the market to merge vertically when there are few related firms, as these subsidized mergers can trigger further vertical mergers and lead to the maximum number of pairwise vertical mergers whereby the monopolistic supplier can grasp the bulk of the efficiency gains stemming from eliminating double marginalization. In contrast, it is more profitable for the essential input supplier to acquire a downstream firm and foreclose other downstream competitors when the number of related firms is large, as the subsidization required by the first strategy grows with the number of the related firms.