鑒於興櫃市場股票交易逐漸熱絡，投資人愈趨關注該市場的相關事件，本研究以興櫃市場中受輔導之公司為樣本、更換主辦輔導推薦證券商為研究事件，探討有更換券商之情事的樣本公司，在事件發生前後是否存有異常報酬，並接續研究這些公司成功上市櫃後，期初報酬率是否顯著異於未有更換之情事發生的新上市櫃公司，進而判斷「更換主辦輔導推薦證券商」事件是否為影響期初報酬率的其中一項因子。 本研究以事件研究法分析事件發生日前後是否存在顯著異常報酬，雖然不論是平均異常報酬率或累積平均異常報酬率都呈下降趨勢，但統計檢定結果顯示並未顯著異於零，因此可判定投資人對於更換主辦券商之情事有負面的反應，但反應程度並不顯著，沒有賺取超額報酬的機會。本研究另外設計多元迴歸模型觀察各項自變數，包含是否更換過主辦輔導推薦證券商、上市或上櫃公司、公司規模、發行總金額、內部人持股比例、平均中籤率、產業別、發行公司年齡等，對期初報酬率的解釋能力，實證結果顯示，平均中籤率愈低、內部人持股率愈高、有更換過主辦輔導推薦券商的公司會有較高的期初報酬率，投資人可依上述三項公司性質作為選取股票的參考。 / In view of the stock trading in “Emerging Market” is becoming more and more popular, Investors are concerned with related event or information about the market. I selected several companies traded in Emerging Market as samples, leading counseling securities replacement as the research event, investigating the sample companies with replacement and whether the abnormal return exists before or after the event happened. I also tracked these sample companies until IPOs, testing the statistical significance of initial return to judge if the “replacement-of-leading-securities” event is one of the factors explaining the existence of initial return. I used event study to test the significance of abnormal return. Both the average abnormal return and the cumulative average abnormal return display a downturn trend during event window, not statistical significant though. Based on the result, I presume the investors have adversely impact on the replacement event, but the impact is not remarkable. There’s no chance to gain the abnormal return. Besides, I set a multiple regression to test the coefficient of each control variable. The empirical result implied that the average success rate, the shareholding ratio of insiders and the companies with replacement event influence the initial return significantly. Investors could follow those three company characters as reference of choosing stocks.