本文利用事件研究法探討台灣股票市場上市公司辦理現金增資的宣告效果，並研究不同承銷制度與證券主管機關修改法規對公司股價的影響。以股東會決議日及證管會核准日為現金增資事件日，研究樣本包含民國85年1月1日到民國94年12月31日間，辦理現金增資的266家上市公司，共計609個有效樣本。實證結果顯示：股東會決議日現金增資宣告之異常報酬為負，證管會核准日宣告效果則不顯著。不同承銷配售方式下，股東會決議日的累積異常報酬有顯著差異：公開申購之負宣告效果較詢價圈購顯著。雖然法規變革對詢價圈購影響較大，但整體而言，法規變革對宣告效果影響不大。影響異常報酬的主要因素為公司年齡，公司成立時間越長，異常報酬越低。 This study investigates the effects of SEO announcements for TSEC listed companies, and the impacts of different flotation methods and underwriting regulation changes on the SEO announcements abnormal returns. The announcement dates are “the stockholders’ meeting authorized date” and “the SEC approval date”. There are 609 samples between 1996 and 2005. We find significant negative abnormal returns on “stockholders’ meeting authorized date” and insignificantly positive abnormal returns on “SEC approval date”. On “stockholders’ meeting authorized date” different flotation methods do affect cumulative abnormal returns significantly. However, underwriting regulation changes have no significant impact on SEO announcements. The main factor that influences abnormal returns is the age of the issues: the older the issues, the lower the abnormal returns.
