本研究從價值低估假說的觀點，採取事件研究法，針對以「為維護公司信用及股東權益所必要」而宣告買回股票之公司及其同業競爭對手之股價反應進行研究，以驗證宣告之訊號效果及產業效果。之後，更進一步透過單變量與多變量迴歸分析，探討影響產業效果的重要因素。
實證結果發現，股票購回宣告除了使宣告公司股價出現異常反應之外，其同業對手的股價亦出現顯著的正向異常報酬率，即股票購回宣告對同業對手股價產生淨蔓延效果。此外，進一步探討與產業效果相關的影響因素則發現，宣告傳達訊息多寡與對手資訊不對稱程度此二因素與蔓延效果呈現顯著的正相關，產業競爭程度與競爭效果呈現顯著的負相關。而「相對規模」、「宣告公司與對手現金流量與投資機會相似度」、「對手價值低估程度」與「對手財務槓桿程度」此四項變數只有在單變量分析中，才能顯現與蔓延效果間的關係。

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目次
第壹章 緒論………………………………………………………………1
第一節 研究背景與動機……………………………………………1
第二節 研究目的……………………………………………………3
第三節 研究範圍與限制……………………………………………4
第四節 研究架構與流程……………………………………………6
第貳章 文獻探討…………………………………………………………8
第一節 股票購回動機與訊號效果…………………………………8
第二節 股票購回之產業效果………………………………………17
第三節 綜合討論與研究啟示………………………………………30
第參章 研究設計….……………………………………………………32
第一節 研究假說……………………………………………………32
第二節 樣本選擇與資料來源………………………………………37
第三節 實證研究方法與變數操作性定義…………………………39
第肆章 實證結果分析…………………………………………………57
第一節 樣本資料與特性……………………………………………57
第二節 股票購回宣告對宣告公司股價的影響……………………60
第三節 股票購回宣告對同業競爭對手股價的影響………………66
第四節 產業效果之單變量與多元迴歸分析………………………73
第伍章 結論與建議……………………………………………………84
第一節 研究結論……………………………………………………84
第二節 研究特色與貢獻……………………………………………86
第三節 後續研究方向建議…………………………………………87
參考文獻……………………………………………………………………88
附錄…………………………………………………………………………96
附錄一…………………………………………………………………96
附錄二…………………………………………………………………102

一、中文部分
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翁鶯娟（2002），「併購宣告對產業內競爭對手公司股價影響之研究－以台灣上市公司為例」，國立成功大學國際企業管理研究所未出版碩士論文，pp.1-47。

游貞旋（2002），「庫藏股宣告對同業股價影響之實證研究」，國立成功大學國際企業管理研究所未出版碩士論文，pp.1-34。

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