本研究探討上市公司宣告發行與正式發行可轉換公司債對於股價報酬率的影響,並配合預期轉換期間觀點的介紹,探討可轉換公司債內含的債卷與權益性質是否影響發行的股價表現.

本研究取樣民國79年至87年2月在臺灣證卷交易所上市的國內可轉換公司債為研究對象,共有69個樣本,分別針對宣告日與發行日前後20個交易日進行異常報酬分析,並且以異常報酬為應變數,預期轉換期間和其他控制變數為自變數進行多元迴歸分析,得到以下的結論:1.臺灣企業發行的可轉換公司債普遍為權益型的可轉換公司債,轉換 期間較短,權益性質較強,因此宣告時股價表現與權益型證卷較類似 ,股價有負面反應.2.預期轉換期間的長短和發行時異常報酬有顯著正向關係,表示預期轉 期間愈長,權益性質愈強,發行時股價表現榆.3.股價報酬率波動度和發行時異常報酬有顯著負向關係,表示股價波動度愈大,內含選擇權的價值愈高,權益性質愈強,發行時股價表現愈差.

The research will analysis the impacts of average and cumulative abcdrmal returns of the underlying stocks of the convertible bonds ann-ouncements and issues by means of events study and GARCH model. And then, we introduce time to expected conversion, we can divide samples into bond-like and equity-like convertible bonds, and through the multipleregression analysis, whether or not there is abcdrmal returns because ofbond and equity characteristics embeded in the convertible bonds can thenbe determined.

Our research will be conducted a convertible bonds set from TaiwanStock Exchange from 1990.4 to 1998.2, the empirical results shows that:1.The convertible bonds issued in Taiwan is usually equity-like, time to expected conversion is very short and equity characterisitcs is very strong, the underlying stock prices is smiliar to equity securities at the announcements of a new issuance and have a negative abcdrmal returns. 2.Time to expected conversion is significant positive to two-day period abcdrmal returns at the issuance day, this results shows that when this time is longer and is easier to converse, the convertible bonds is more equity-like and negative effects of the underlying stocks is larger. 3. The volatility of underlying stocks is significant negative relation to two-day period abcdrmal returns at the issuance day, this results shows that when this volatility of returns is larger and it can increase the value of the options embeded in the bonds, the convertible bonds is more equity-like and negative effects of the underlying stocks is larger.