藥品發展事件的公告，對藥廠市場價值之影響？以輝瑞公司為例

Do Public Announcements of Drug Development Events Influence a Drug Company's Market Value? A Study on Pfizer

全球藥品市場規模逐年增加，故藥品研發成功對藥廠至關重要。本研究採用事件研究法來探討輝瑞公司各類藥品發展事件的公告日前後股價異常收益。本研究目的（1）探討藥品發展事件在政府資料庫及大眾媒體報導等兩種公告日前後輝瑞公司股價波動，（2）檢視這些事件是否會影響輝瑞公司競爭對手的股價，以及（3）比較這些事件在公告日期前後的股價波動差異。研究結果顯示輝瑞公司的股價在媒體揭露獲得藥證和訴訟判決結果等事件前就已有顯著波動，但是其他競爭對手的股價不會與其連動。值得注意的是，大眾媒體的報導日期與政府資料庫的公告日期間存有時間差且股價波動也不同。本研究成果可作為股票投資時的判斷依據，以及藥品研發時的資源配置參考。

The circulation of money in the global pharmaceutical market is substantial and has been increasing annually. Moreover, the high requirements for new drugs and the procedures for verifying the quality of drugs are increasingly complex; thus, successful drug research and development are critical for drug companies. To identify fluctuations in stock prices during the drug research and development process, the event study model is adopted to capture abnormal returns in Pfizer stock resulting from the public announcement of various relevant events. The study aims to (a) examine whether events publicized by official databases or the media during drug research and development affect Pfizer's stock price; (b) examine whether these events affect the stock price of Pfizer's competitors; and (c) compare price fluctuations around the dates of these events. The event data are collected from official databases, including the US Food and Drug Administration's Orange Book; clinicaltrials.gov; Web of Science; and media sources, such as the Wall Street Journal. The collected data span from the first date in each data source to December 31, 2018. The results reveal that Pfizer's stock price is affected by drug approval dates and trial judgment dates prior to media reports. However, the stock prices of other competitors are not correlated with Pfizer's stock price. Notably, a time gap between reporting from the Wall Street Journal and other data sources is identified. The results of this study can be useful for investors in the global stock market and for pharmaceutical companies exploring resource allocation in drug research and development strategies.