異質信念(Heterogeneous beliefs)修正傳統資產定價理論中同質信念(Homogeneous beliefs)的基本假設，探討投資者間所持有的不同資訊，以及對於資訊的不同參考程度，如何影響資產定價。 本文試圖以Banerjee(2008)的模型，估計出臺灣投資者對於台灣各家公司股票的價格參考密度；並且透過外部研究者的預測作為市場不同信念的代理變數，探討異質信念對於臺灣股市交易的價量影響。 經由實證結果發現，在台灣的股市交易市場上，當市場的資訊流通速度愈快，投資者對公開資訊的參考密度愈低，投資者愈易依賴自己所持有的私人資訊。當投資者的行為決策將愈顯紛歧時，對交易量和報酬率的影響皆為正。 / Heterogeneous beliefs, which revise the basic assumption of traditional asset pricing theory- Homogeneous beliefs, study the impact on asset pricing by different information owned and referred by investors. I use the model derived from Banerjee(2008)to estimate the degree how Taiwan investors will take into account stock prices when they make investment decisions. Also, I study how heterogeneous beliefs of investors influence stock prices and trading volume in Taiwan stock market, using predictions of external researchers as a proxy variable of dispersion in beliefs. The empirical results show that the degree which investors take into account prices will be lower when a faster information flowing speed exists in Taiwan stock market. When investors rely more on their private information, their investment decision will become much diversified. Dispersion in beliefs has a positive influence on stock trading volume and return.

本研究旨在探討我國生醫產業公開說明書之資訊揭露程度對初次公開發行 (IPO, initial public offering)定價效率及次級市場投資人信念異質性程度之影響。當初級市場認購人間資訊不對稱程度越大時，IPO價值之事前不確定性越高。為均衡各交易參與者之利益，發行人與承銷商將主動提升公開說明書之資訊揭露程度，以制定適當的IPO折價幅度、維持承銷商合理的承銷風險與報酬，並協助認購人適切評定IPO之價值。異質信念觀點強調次級市場投資人對企業價值看法之歧異程度越大，將導致IPO蜜月期報酬之異常現象。本研究預期若無形資產密集度越高，IPO事前不確定性越大，則IPO折價幅度越大，並預期公開說明書之資訊揭露程度將改變無形資產密集度對折價幅度之影響程度。此外，本研究預期，生醫產業IPO案件之無形資產密集度、公開說明書之資訊揭露程度及者配售情形均可能影響投資人信念異質性，進而影響掛牌初期之成交價量表現。 本研究參考國外證券主管機關之無形資產資訊揭露規範，自行建立資訊揭露指標，系統性地衡量我國生醫產業公開說明書之資訊揭露程度，並以多元迴歸分析檢測假說。實證結果顯示，我國生醫產業IPO案件之無形資產密集度對IPO折價幅度存在顯著正向影響；公開說明書之資訊揭露程度改變無形資產密集度對折價幅度之影響程度；發行人之無形資產密集度、公開說明書資訊揭露程度及初級市場配售情形皆影響掛牌初期之投資人信念異質性及價格震盪幅度。研究結果證實公開說明書之資訊揭露提供預期效益，及初級與次級市場間之資訊相互流通、交易行為相互連動之關聯性。 / This research examines how the disclosure level of prospectus influences the efficiency of IPO (initial public offering) pricing in the primary market and the degree of divergence of opinions in the secondary market. The literature of IPO underpricing suggests that ex ante uncertainty due to information asymmetry has a positive impact on IPO discount and voluntary disclosure of prospectuses may reduce the uncertainty level. This research hypothesizes that, for biotechnology companies, a greater disclosure level of prospectuses would lower the impact of intensity of intangibles on IPO discount. Further, this research hypothesizes a relation between the pricing efficiency in primary market and the level of divergence of opinions in secondary market. The empirical results from regression analyses of hand-collected data show that, for biotechnology IPOs, the disclosure level of prospectuses reduces the impact of the intensity of intangibles on IPO discount. In addition, the intensity of intangibles, disclosure level of prospectuses, and trading behaviors in the primary market have an effect on the degree of divergence of opinions in the secondary market. In sum, this research evidences the expected benefits of the increased level of voluntary disclosure of prospectuses for biotechnology IPOs.