胖達人於2013年由盈轉虧，內部投資者得知消息後，共謀在虧損消息曝光前出脫持股規避損失。透過上述事件中，我們不禁產生了疑問，在自然人投資者當中，是否有些投資者如同胖達人事件是具有私人訊息呢？而自然人投資者從交易中的獲利是因為私人訊息嗎？
　　本文研究盈餘宣告時自然人投資者的交易情形，並同時與外資、投信及一般公司投資者做比較，以盈餘宣告當日及其前後之各類投資者的交易與報酬率、盈餘驚喜以及淨交易之間的關係進行實證分析。
　　透過我們的資料所做出的證據顯示，外資與投信皆沒有特別顯著之顯示其具有訊息，而對於一般公司所做出的分析則皆為不顯著，表示一般公司是不具有私人訊息的，但本文對於自然人投資者是否具有訊息卻產生了兩種不同的解釋，一個是自然人投資者確實具有訊息，因為其具有正確操作，其投資預視了未來的市場走向，表示遵循著自然人投資者的交易還是有利可圖的。另一個是自然人投資者是沒有訊息的且沒有具有訊息的優勢，而是看著消息買進股票或賣出股票，所以經常成為損失的一方。
　　對此，我們做出下列這樣的解釋，在自然人投資者當中，有些自然人投資者是屬於具有訊息的大量交易者，而有些自然人投資者則是屬於無訊息的小量交易者，但本文取得的資料只能看出自然人投資者的整體，而不能去區分哪些自然人是屬於大量交易者以及那些自然人是屬於小量交易者，因此本文對自然人投資者產生了不同的分析結果，其可能在進行分析時，資料所顯現出的是因小量交易者所造成，抑或是大量交易者所造成的。

　　Insider investors allegedly sold shares of Top Pot before news was released in 2013, which avoiding losses of 60 million. Because of this event, I have some questions about the individual investors. For the individual investors, whether Top Pot Bakery's insider investors utilize the private information to prevent losses? Do insider individual investors gain from the private information trading?
　　The purpose of this study is to investigate the transactions of individual investors around earnings announcement, and compare the results with the trading behavior of foreign investor, investment trust and corporation. This study analyzes the relationships among rate of return, earnings surprises and net trading of types of investors, and try to find the evidence that whether the individual investors gain from private information trading.
　　We do not find significant evidence that foreign investor, investment trust and corporation are informed traders. But we find two opposite trading phenomena for individual investors. One is the individual investors are informed traders that they have right trading direction before the event and therefore forecast the future market direction. In other word, it means that following the individual investor's trading is profitable. Another evidence shows the individual investors are non-informed traders. They buy stocks following good news and sell stocks following bad news. The trading behavior let individual become a loser.
　　For the evidence I find, I guess there are two different types of individual investors, one is informed large traders and the other is non-informed small traders. For future study, more rich database is needed.

摘要i
誌謝辭iii
目錄iv
表目錄vi
圖目錄vii
第一章 緒論1
第一節 研究背景與動機1
第二節 研究目的2
第三節 研究流程3
第二章 文獻探討4
第一節 訊息不對稱4
第二節 訊息對自然人投資者的影響8
第三節 自然人投資者之行為探討10
第四節 盈餘宣告17
第三章 研究方法26
第四章 實證研究30
第五章 結論與建議38
參考文獻41

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