本文探討當進口國政府實施市場份額的自動進口擴張政策 (VIE)時，在考慮產量決定者和市場結構差異的情形下，市場均衡與社會福利水準相對Cournot數量競爭的差別，以及對進口國而言，VIE政策的實施真的是符合其利益的「自動」政策。本文結論如下。在僅有一出口國廠商和一進口國廠商的兩國雙占模型中，VIE政策會使得市場競爭程度降低，兩廠商間的產量和將會是勾結解。當出口國廠商為產量決定者時，相對Cournot數量競爭，出口國的廠商利潤和社會福利均會提高；進口國廠商利潤的增減要視兩廠商相對成本高低才能判斷，而進口國社會福利必會降低。當進口國廠商為產量決定者時，進口國與出口國廠商利潤皆會因VIE而提高，此時，出口國的社會福利會因利潤的增加而上升，進口國的社會福利則會因消費者剩餘的損失大過利潤的增加而降低。在考慮存有另一出口國廠商的三國模型中，當要求實施VIE政策的出口國廠商為產量決定者時，兩出口國的廠商利潤和社會福利均會增加，進口國會受制VIE的要求，使其利潤和社會福利皆減少；若進口國為產量決定者且要求實施VIE政策的出口國廠商成本劣勢明顯時，另一出口國廠商會因VIE而受害，其餘兩廠商則會因VIE而受益，故此條件的VIE可促使進口國的廠商利潤和社會福利皆提高。 The thesis analyses the effects of different output deciders and market structure when importing country implements market-share voluntary import expansion (VIE) policy. We show that a VIE may be truly voluntary for importing country. In a two-country duopoly model with Cournot competition, when importing country adopts VIE as a policy instrument, it will lower market competition, and facilitate market output collusive outcomes. It is shown that the output deciding firm, who determines output first, the monopoly results will depend on output decider’s marginal cost. Furthermore, the exporting country’s social welfare and firm’s profit will enhance under VIE policy, but importing country is uncertain about these results. In a three-country oligopoly model, when the importing firm acts as an output decider with a higher cost firm that petitions for VIE assistance, importing country will be better off under market-share VIE.
