International arbitrage and the extensive margin of trade between rich and poor countries*
将消费不可分割性引入克鲁格曼模型，发现进口国人均收入决定“出口为零”现象，富国企业为避免国际套利而放弃向穷国出口，贸易自由化使富国受益、穷国受损。
We incorporate consumption indivisibilities into the Krugman (1980) model and show that an importer's per capita income becomes a primary determinant of “export zeros”. Households in the rich North (poor South) are willing to pay high (low) prices for consumer goods; hence, unconstrained monopoly pricing generates arbitrage opportunities for internationally traded products. Export zeros arise because some northern firms abstain from exporting to the South, to avoid international arbitrage. Rich countries benefit from a trade liberalization, while poor countries lose. These results hold also under more general preferences with both extensive and intensive consumption margins. We show that a standard calibrated trade model (that ignores arbitrage) generates predictions on relative prices that violate no-arbitrage constraints in many bilateral trade relations. This suggests that international arbitrage is potentially important.