Oligopoly and oligopsony in international trade
研究了国际贸易如何影响企业在投入品市场的寡头买方垄断势力，发现贸易自由化在降低最终品市场垄断势力的同时，会增强投入品市场的买方垄断势力，导致单位成本加成可能净增加。
Abstract We study the effects of international trade on the oligopsony power of firms in input markets. We build a theoretical model of international trade in which firms are oligopolists in the market for final goods and oligopsonists in the market for inputs. Consistent with evidence from the literature, firms' markups over unit costs rise with the level of oligopsony power and of oligopoly power. While trade liberalization decreases market power in one market, it has the opposite effect in the other. In particular, international competition between oligopolists in final goods markets causes oligopsony power to increase and oligopoly power to decline. In a simulation, we show that the increase in oligopsony power can more than offset the reduction in oligopoly power, resulting in a net increase in markups over unit costs.