我國自西元2000年8月9日經財政部證券暨期貨管理委員會(目前的行政院金融監督管理委員會-證期局)公告，庫藏股制度正式實施，並公布「上市上櫃公司買回本公司股份辦法」作為上市櫃公司作業依循，法令規定上市(櫃)公司在符合一定條件下可買回自家公司流通在外股份，相對減少企業透過非正式管道購回股票之例外管理，藉由庫藏股實施的公告制度也減低了投資人資訊不對稱的程度，庫藏股實施已成為企業財務運作的一項重要工具。
本文主要探討庫藏股購回及現金減資對企業股價與營運的影響，包括宣告購回股票企業的價格、目的、數量、作業期間及影響因素等，針對各變項進行研究，以瞭解各因子對實行庫藏股購回之影響，再就「庫藏股」與「現金減資」進行比較，以分析不同工具之影響效果。經研究整理後，本文結論如下：
一、公司實施庫藏股購回具有短期宣告效果。
二、公司股價遭低估，當市價/淨值比越低，宣告購回股價反應越大。
三、庫藏股購回之目的與意圖符合宣告效果，購回目的「為發放員工」不若「為維護股東權益」的累積平均異常報酬明顯。
四、庫藏股購回實施，多數企業未增加企業價值。
五、庫藏股購回作業期間縮短對買回期間股價並無影響。
六、宣告購回日平均量佔宣告日前實際成交日平均量比率越大對股價上漲為正向影響。
七、庫藏股宣告效果影響因素中以市價/淨值比呈顯著相關，顯然股價低估為造成公司購回股票的主要因素之一。
八、「庫藏股購回」較「現金減資」方式具有較高的累積平均異常報酬，而實際報酬則產生相反情況，主要為「現金減資」於宣告日前股價為正報酬，與「庫藏股」宣告日前股價為負報酬呈現明顯對比，庫藏股於宣告日後股價由下跌轉為上升，現金減資則於宣告日前為上升趨勢，宣告日後股價持續上揚，顯示現金減資公司財務體質建全並長期遭到低估，與庫藏股受到短期股價下跌，經宣告購回所產生的短期回升，兩相比較具較大差異。
針對後續研究，可選擇考量公司治理、財務結構、營運資金流量、獲利狀況、股利發放、內部關係人交易資訊、實施後對企業效益與影響及企業生命週期等，針對庫藏股購回或現金減資等財務工具的運用時點及變項加入考量，以進一步分析「庫藏股」及「現金減資」施作對企業營運所產生之各種效應。

The Share Repurchase Regulation was officially established by Security and Future Committee, Ministry of Finance (now Security and Future Bureau, Financial Supervisory Commission) on 9th of August 2000, alongside with the “Regulations Governing Share Repurchase by Exchange-Listed and OTC-Listed Companies” for applicable organizations. The regulations state that the Exchange-Listed and OTC-Listed companies are able to repurchase the shares from the stock exchange and OTC market under specific conditions, and therefore decrease the exceptional management of share purchasing via unofficial channels. By establishing the regulation, the unbalance of information among investors is eased, and makes Share Repurchase become an important tool in corporation financial operation.

This article has several conclusions:
1.The Share Repurchase has short term announcement effects on corporations.
2.When the corporation’s share price is undervalued, the market price/net book value ration is in opposite direction wit the price of announced share prices.
3.The purposes of Share Repurchase meet the announcement effects. The Cumulative Average Abnormal Return is more advantage when the repurchase purpose is “maintaining shareholders’ profitability” rather than “returning to the employees”.
4.No corporation values are added during the adaptation of Share Repurchase in most of the cases.
5.No effects occur on share prices while holding if the process time of Share Repurchase is shortened.
6.The greater ratio of announced repurchase average shares/actual dealt average shares before announcement, the more positive effects on the share price.

7.The market share value/net book value ratio is noticeably relating to the Share Repurchase announcement effects. Therefore share price undervalue is one of the main reasons to prompt corporations carry out share repurchase.
8.“Share Repurchase” policy produces higher Cumulative Average Abnormal Return than “Capital Reduction”, whereas the normal return is in contrary. The main difference is the profitability of shares before and after the announcement of “Share Repurchase” or “Capital Reduction” policies. By announcing Share Repurchase, the corporation’s share price will soar temporarily and get around the short term slip on share price, while Capital Reduction will endorse the increasing share price as the adapting corporation has healthy financial structure and been undervalued by the markets at length.
For further research, several aspects and attributes, including corporation governance, financial structure, operational cash flows, corporation profitability, dividend, internal Related Persons trading information, effects on corporation efficiency, and corporation life cycle, can all be considered in conjunction with the significance of financial tools’ application timing and their variables, hence facilitating the analysis of the effects and results on the corporations’ operation after adapting “Share Repurchase” and “Capital Reduction” policies.

一、中文文獻
(一)、王日進，「股票買回與盈餘管理相關性之研究」，碩士論文，南台科技大學會計資訊研究所(民94)。
(二)、李憲彥，「台灣上市公司庫藏股購回宣告效應之研究」，碩士論文，國立中央大學企業管理所(民94)。
(三)、汪瑞芝，「庫藏股買回對公司績效之影響」，中華管理評論國際學報2008年2月第十一卷第一期(民97)。
(四)、邱垂昌，「宣告及實施買回庫藏股與異常報酬-管理者之策略性應用」彰化師範大學，會計與公司治理2006年12月第三卷第二期(民96)。
(五)、邱鍵麟，「台灣上市公司實施庫藏股制度對股價影響之研究」，碩士論文，長庚大學企業管理研究所(民90)。
(六)、陳達新，「庫藏股制度對股票價格的宣告效果-台灣上市公司之實證研究」淡江大學財務金融系，商管科技季刊民國九十二年第四卷第四期(民92)。
(七)、曾欽冠，「台灣上市公司庫藏股購回效應之研究」，碩士論文，南華大學財務管理研究所 (民96)。
(八)、湯翠萍，「財務彈性-上市公司實施庫藏股之實證研究」，碩士論文，國立中山大學財務管理研究所(民93)。
(九)、詹雅惠，「股票購回與現金股利政策變動宣告效果之研究:以台灣上市電子公司為例」，碩士論文，國立臺灣科技大學財務金融研究所(民95)。
(十)、戴正雄，「公司治理對股利政策與庫藏股決策之影響」，碩士在職專班論文，輔仁大學會計學系(民95)。
(十一)、謝育政，「實施庫藏股制度對公司股價影響之研究」，碩士論文，國防大學國防管理學院資源管理研究所(民90)。
二、英文文獻
(一)、Gustavo, G and Roni, M, “The Information Content of Share Repurchase Programs,”The Journal of Finance, VOL. LIX, NO.2, pp.651-681 (2002)
(二)、Ikenberry, D., Lakonishok, J. and Vermaelen, T., “Market Underraction to Open Market Share Repurchase,” Journal of Financial Economics, Vol. 39, No. 2-3, pp. 181-208 (1995)
(三)、Kamala R. Raghavan, “Are Share Repurchases Effective Signals to the Market? ”, Bank Accounting & Finance,June-July, pp. 27-48 (2006)
(四)、Larry Y .Dann, “Common Stock Repurchases: An Analysis of Returns to Bondholders and Stockholders,” Journal of Financial Economics, Vol. 9, No. 2, pp. 113-138 (1981)
(五)、Pierre-Emmanuel QUINTANA, “Open Market Share Repurchases And Their Signaling Power: The French Experience, 1998-2006”,HEC Paris-Finance Major , French (2006)
(六)、Ranjan D’Mello and Pervin K.,“Equity Undervaluation and Decisions Related to Repurchase Tender Offers: An Empirical Investigation,” The Journal Of Finance , VOL. LV, NO. 5 pp.2399-2424 (2000)
(七)、Vermaelen, T., “Common Stock Repurchases and Market Signalling,” Journal of Financial Economics, Vol. 9, No. 2, pp. 139-183 (1981)