近年來國內企業減資行為大幅增加，依據證劵交易法及公司法，企業減資的類型分為三種：(1)庫藏股減資(2)彌補虧損之減資 (3)現金減資。本文以台灣上市上櫃公司為樣本，以事件研究法分析企業進行減資對其股價異常報酬之影響，研究過程以市場模式的最小平方法(OLS)針對三種減資類型進行分析，探討股價是否存在異常報酬；再以橫斷面複迴歸分析探討影響企業減資的股價異常報酬的因素。實證結果發現，企業實施減資行為時，其公司股價在事件日期間均呈現顯著正向的累積異常報酬，代表市場對於企業減資的行為有立即反應的顯著效果；實施庫藏股減資的公司，具有顯著正向的股價反應，代表投資人將此一減資訊息是為公司股價被低估的有利消息；實施減資以彌補虧損的公司，在事件日後累積異常報酬呈現正向顯著；實施現金減資的公司，市場上多為正向股價反應。企業實施減資行為的股價異常報酬確實與淨值市價比率、負債比率、現金流量比率等公司財務比率相關。
Recently, domestic enterprises reduced capital a lot. According to Securities and Exchange Law and Company Law, capital decreases are divided into three types (1) treasury stock, (2) compensation of loss, (3) capital reduction by cash. This study used event study that ordinary least squares (OLS) is applied to evaluate the abnormal returns of capital reduction in Taiwan listed companies. Besides, cross-sectional multiple regression is applied to investigate the factors to impact the abnormal returns of capital decreased companies. The empirical results show that when the company to carry out capital decrease, the company’s stock price have significantly positive cumulative abnormal returns during the event periods. It represents that market will response to the events immediately and significantly. The company with treasury stock have significantly positive cumulative abnormal returns. It represents that investors use the message of capital decrease as favorable news for the company's stock price. There will have significantly positive cumulative abnormal returns after the event date of the company with the capital reduction to compensate for loss. The company with the capital reduction by cash will have significantly positive cumulative abnormal returns in the market. The abnormal returns of the companies with capital decrease are related to financial ratios including book-to-market ratio, debt ratio and cash flow ratio.
