本文主要目的，是要檢測臺灣股市過度反應現象是否由股本膨脹效應所致。我們除了首度在文獻上，引進股本膨脹率這個因素去解釋臺灣股市過度反應現象外，和國內其它過度反應文獻不同之處在於，我們樣本採用Laughran及Ritter (1996) 的觀點，包含所有測試期停止交易股票，以避免生存者偏誤的影響。結果發現，即使我們考慮生存者偏誤的問題，臺灣股市仍存在著股本膨脹效應，規模效應，低價股效應和過度反應現象。最後，我們以市值、股價和形成期股票報酬率為控制變數，將測試期股票報酬率，對股本膨脹率Fama-MacBeth迴歸分析發現，股本膨脹率是解釋過度反應的唯一變數。這結果隱含，財政部抑制上市公司股本膨脹，以避免臺灣股市的暴漲暴跌的作法，也許是可行的。

This paper is to investigate whether capital-based growth rate Effect causes overreaction in Taiwan stock market. Following Laughran and Ritter (1996)model, our sample includes all stocks in the Exchange, whether active or not, to avoid the survivor bias,. Our results show that capital-based growth rate effect, firm size effect, low price effect and overreaction effect exist in Taiwan stock market. Moreover, applying the Fama-MacBeth analysis, we find that capital-based growth rate is the only factor that is able to explain overreaction in Taiwan stock market. Our results support the recent policy of Ministry of Finance to limit the listing companies' growth in their outstanding shares in order to reduce the volatility of the market.