本研究選取基亞研發新藥PI-88三期臨床試驗進程之兩個重大訊息發布日，以台灣上市(櫃)生技公司為研究樣本，採用事件研究法對事件日宣告與台灣上市(櫃)生技公司之股價關聯性作實證研究，並分別以兩種不同基準報酬驗證其平均異常報酬差異，以確保結論的正確性。 第一種是以基亞為基準檢定生技組合異常報酬，第二種是以等權、規模或淨值市價比等三個組合當作基準檢定生技組合異常報酬。實證結果發現:事件日2013.12.30基亞與生技股兩者之平均異常報酬呈現符號並不相同，似乎生技股並無因基亞PI-88達成收案目標而有所影響，不過可以發現基亞報酬波動幅度大於生技股報酬，且存在顯著異常差異。事件日2014.7.28之生技股則呈現負的平均異常報酬，且存在顯著異常差異，很顯然生技股的確受到基亞PI-88期中分析報告結果不如預期影響而呈現負向效應；另結果發現西藥股之負向效應並無顯著異於生技類股。 This paper presents an empirical study using the event research method. The study examines the correlation between the stock prices of listed biotechnology companies in Taiwan on the two announcement dates of important developments of the phase 3 trial of PI-88, a new drug developed by Medigen Biotechnology Corp. Two methods are employed to verify the average difference between abnormal returns and ensure that the conclusion is correct. The first method uses Medigen Biotechnology Corp. as the basis for finding the abnormal return of an investment portfolio in biotechnology companies; the second method uses a combination of equal weight, scale and price-net worth ratio for finding the abnormal return of an investment portfolio in biotechnology companies. Findings are as follows: the average abnormal returns of Medigen Biotechnology Corp. and biotechnology companies had different signs on 2013.12.30. It seems that biotechnology stock prices were not influenced by PI-88 reaching its target enrollment, but fluctuation of return on Medigen Biotechnology Corp. was greater than biotechnology stocks, and the difference between their abnormal return reached the level of significance. Biotechnology stocks had a negative average abnormal return on 2014.7.28, and the different reached the level of significance, showing that biotechnology stocks were negatively impacted by mid-term analysis results of PI-88 not meeting expectations. Furthermore, the negative impact on Western medicine stocks was not significantly different from the impact on biotechnology stocks.