本研究主要目的係透過事件研究法驗證上市公司減資宣告之效果，針對符合樣本敘述之企業取樣，以事件研究法進行實證研究，結論如下：
1.有關庫藏股註銷減資宣告，在宣告日當日以及後續幾日並無明顯宣告效果，僅在宣告日前後有零星幾日之顯著異常報酬，並不能強力證明庫藏股購回註銷之減資宣告具有顯著宣示效果。
2.觀察公司宣告庫藏股購回註銷減資宣告之標準化累積平均異常報酬發現，在事件日前後累積平均異常報酬均呈持續上升現象，此效果雖非由此事件宣告而形成，但整體績效於宣告日後股價持續上揚，仍可說明此一宣告並無負向之效果。
3.企業依公司法宣告減資，事件日之前並無顯著異常報酬出現，但在事件日後1-4日，產生顯著之負向異常報酬，顯示股市對於此一事件有即時的反應。
4.觀察依公司法宣告減資事件之標準化累積平均異常報酬發現，在事件日起至事件期結束，標準化累積平均異常報酬持續呈負向走勢，顯示此一宣告影響為負向。
5.透過二組不同事件期設定比較，觀察二類事件標準化累積平均異常報酬觀察發現，不同事件期對分析結果並無影響。

This study examines the market reactions to capital decrease announcements of Taiwan’s public-listed companies by event study market model. Major findings can be summarized as follows：
1.The effect of cancellation of stock repurchased announcement does not show significant abnormal returns. During the event period, there are a few significant abnormal returns before and after the event date. However, it cannot prove that the announcement is significant.
2.Observing the cumulative abnormal returns effect of cancellation of stock repurchased announcement, we found that it is upward during the event period. However, since it cannot be proved being induced by this event, we concluded that this event is not a bad news to market.
3.In another case, the effect of capital decrease announcement according to the Corporate Regulation doesn’t show significant abnormal returns before event date. There are significant negative abnormal returns from day 1 to day 4. It indicates that market reaction to this event is instant.
4.According to the cumulative abnormal returns effect in capital decrease announcement case, we found that it turns from upward to downward from the event date to the end of the event period. Therefore, we concluded that it can be proved being induced by this event; this event can be treated as a bad news to the firms.
5.Comparing the effect of cumulative abnormal returns on two events in different event periods, we found different event periods do not influence the results.

第一章　緒論 1
第一節　研究背景與動機 1
第二節　研究目的 4
第三節　研究架構 4
第二章　文獻探討 6
第一節　現行減資方式介紹 6
第二節　文獻探討 13
第三章 研究方法 22
第一節　研究假說與研究設計 22
第二節　事件研究法 24
第三節　研究限制 33
第四章　實證結果分析 34
第一節　研究範圍與對象 34
第二節　實證資料檢定 37
第五章　結論與建議 53
第一節　研究結讑 53
第二節　研究建議 54
參考文獻 56

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