傳統產業結構大多假設廠商的進入市場時序爲外生給定，並未討論廠商爲何選擇「先後進入市場」(即市場爲「Stackelberg領導者/跟隨者競爭」)或是「同時進入巾場」(即市場爲「Cournot數量競爭」)。本文建構一個混合雙佔模型，探討外資持股變化對廠商最適進入市場時序的影響。本文的分析結果指出：當民營化程度很高(低)時，其均衡進入時序爲Cournot數量競爭(公營廠商爲領導廠商或爲跟隨廠商)，且上述均衡完全不受外資持股比例之影響。但是當民營化程度屬中間值時，隨著外資持股比例之增加，均衡進入時序依序會由公營廠商爲領導廠商或跟隨廠商，演變成公營廠商必然爲一跟隨廠商，再演變成Cournot數量競爭。此外，其它條件不變下，外資持股的增加，可能使本國社會福利不降反升。這些結果與既有文獻之結論迥異。

Considering partial privatization of a public firm, this paper investigates the impacts of foreign ownership on endogenous timing in a mixed duopoly. We find that if the degree of privatization is high (low), the equilibrium is Cournot competition (public leadership or private leadership), irrespective of the foreign ownership ratio of the private firm. Nevertheless, if the degree of privatization is at an intermediate level, the equilibrium becomes sensitive to the degree of foreign ownership, changing from either public leadership or private leadership to private leadership, and finally to Cournot competition. Moreover, to our surprise, social welfare may increase with the foreign ownership. This result stands in stark contrast to previous literature, which asserts that foreign ownership always lowers social welfare.