本研究以總統(副總統)選舉及立法委員選舉事件為主。對於外資及本土機構投資人在選舉後對於股票市場的反應進行分析，並檢測三個月及六個月的股票報酬。本研究預期看好公司發展的持股增加公司，在未來股價上面表現較佳。前景令人堪憂的持股減少公司，在未來股價表現方面較差。本研究預期本土機構投資人相較於外資為資訊取得優勢者，因此，在政治選舉事件後，對於各公司未來的發展能有專業且較深入的剖析，進而對於公司有較正確的持股調整。因此，就持股增加公司而言，本土機構投資人於選後一段期間的股票報酬會顯著高於外資。就持股減少公司而言，本土機構投資人於選後一段期間的股票報酬會顯著低於外資。實證結果發現，本土機構投資人因具有資訊取得優勢，對於台灣的政黨政策及理念、整體經濟環境，甚至是台灣激烈的選戰後所帶來的影響能有精闢的分析與見解，進而做出正確的投資判斷。;This paper is based on presidential (vice- presidential) election and legislative election. After election, we analyze the reaction difference between QFII and domestic institutional investor in stock market and test 3 month and 6 month stock return. If a company has a promising future, investors will increase the proportion of shareholding and stock price go up in the future. If a company doesn’t have a hopeful future, investors will decrease the proportion of shareholding and stock price go down in the future. We hypothesize domestic institutional investor can make a better investment and have a better adjustment for the proportion of shareholding in stock market. The main reason is that domestic institutional investor have superior information and they can make a deep analysis of company. Therefore, stock return for domestic institutional investor will be higher than QFII in a company which increases the proportion of shareholding. Stock return for domestic institutional investor will be lower than QFII in a company which decreases the proportion of shareholding. We find that domestic institutional investor make a better investment because they have advantage in getting more information and they can make an incisive analysis in party’s policy and future prospect in a company.