生物科技公司盈餘宣告對股價之影響

Abstract

本研究採用事件研究法，選取40家上市上櫃生物科技公司作為樣本，檢視樣本公司公佈2003年及2004年盈餘宣告對股價之影響情形。經本研究顯示當生物科技公司發布盈餘時，其股價反應，主要發現如下： 1. 當盈餘衰退資訊發佈時，2003年及2004年市場股價均呈現負向反應，顯示其股價已回歸至其基本面之表現。 2. 當發佈盈餘成長之資訊時，2003年及2004年市場股價卻都未呈現正向反應。可能係其部分生物科技公司的盈餘水準不如其當年度所公開的財務預測，或受其他因素所導致。 3. 2003年股價的反應幅度與2004年的反應幅度相較比較大 4. 上述現象也有可能係投資人心理層面的影響，導致股價的反應不如預期。

This research applies the event study approach to examine how declaration of earnings affects a company’s stock price. Stock prices of forty listed biotech companies in Taiwan in the 2003-2004 period are collected for analysis. The major findings are as follows:

1. When a company announces falling earnings, its stock price then significantly goes down, showing that stock prices are significantly affected by fundamental factors. 2. If a company reports growing earnings, its stock price then usually fails to positively respond. This may be because the actual earnings are still unable to meet the targets in their financial forecasts. 3. Compared to those in 2004, fluctuations in stock prices reacting to financial declaration in 2003 are relatively larger. 4. These phenomena can be explained investors’ bounded rationality and psychological factors.