在混合寡佔模型中，民營廠商部分持有公股並需繳納股權金下，本文發現在無附加預算限制時，最適政策為完全民營化；附加公營廠商預算限制時，最適政策為保持公營廠商完全國有化。經進行福利比較分析後，唯有對公營廠商無附加預算限制並完全釋股時，提昇公營廠商競爭力才會有較高的社會福利水準。

We show that in the presence of cross-ownership associated with an improvement of production inefficiency of the public firm, the optimal privatization policy is full privatization in the absence of budget constraint, while the optimal privatization policy when the government imposes a budget constraint is full nationalization without free private entry. The important implication on budget constraint and privatization policy is that the government should not impose budget constraint on the public firm but needs to adopt full privatization policies for achieving higher social welfare.