Economies of scale and market structure in international grain trade
构建了一个双寡头模型，分析私人贸易商与国营贸易企业在国际谷物市场上的竞争，发现外部冲击、产品差异和竞争模式会影响市场结构和份额。
Abstract A large body of literature has examined international grain trade in imperfectly competitive models. The article develops a two‐stage duopoly model that considers a private trader and a State Trading Enterprise (STE) competing on a foreign market. The key difference between the private trader and the STE is their international organization; while the STE makes use of external agents to export, the private firm may choose to internalize international transactions. The game is solved for different modes of competition and under both assumptions of homogeneous and differentiated products, in order to assess how these assumptions affect the outcome of the game. The results of the game are examined by using numerical examples. The analysis shows that external shocks on export markets may result in a change of market structure and, consequently, of market shares. These effects depend on the initial market structure. Furthermore, the degree of product differentiation and the assumed mode of competition significantly affect the relative values of transaction and fixed costs at which the market structure changes.