「為何要禁止內線交易行為？」國內外學者就此問題提出「健全市場」、「平等保護」或「信賴關係」等理論加以解釋。本文之研究，乃企圖以法律經濟學觀點重新思考此一問題。從內線交易具有鼓勵內部人從事創新活動之報酬效果，以及有助股價正確性而言，內線交易似具有相當之效率性；自取得資訊管道的優勢以及保護交易相對人（即投資人）角度思考，內線交易也未必係不公平的。因此，基於公平或市場健全等理由禁止內線交易，遭遇到許多挑戰，法律經濟學者進而提出「資訊財產權理論」作為禁止內線交易的內涵。該理論認為公司內部未公開之重大消息係公司之無體財產權，內部人不得為自己或他人之利益使用該資訊財產。本文除分析並討論資訊財產權理論外，亦從該理論角度重新檢視我國內線交易內部人範圍的兩個爭議問題，即公司本身是否屬內線交易的內部人？以及公務員於何種情況下屬於「基於職業關係」獲悉消息的內部人？以期對學說與實務爭議提供一不同的思考方向。

”Why should the law prohibit corporate insiders from insider trading?” In response to this question, scholars have provided various theories, including market integrity, equal access to information or fiduciary relationship, etc. This paper is trying to rethink this question from the perspective of law and economics. Two major reasons to support insider trading: first, insider trading is an efficient way to compensate managers; second, insider trading can increase the market efficiency. Also, from the standpoint of information asymmetry among investors, market professionals and insiders as well as the standpoint of protection of investors, insider trading is not necessary unfair. Therefore, scholars in law and economics provide another theory as the basis for prohibiting insider trading, namely, the property right in information theory. This theory suggests that the material non-public corporate information is the intangible property right of a company. Insiders can not use that property for the benefits of themselves or of the third party. In addition to discussing and analyzing the above property right theory, this paper also focuses on two issues regarding the scope of insiders: first, does a company itself fall within the definition of insiders? Second, when a government employee will be considered to be an insider by reason of occupational relationship? By applying the property right theory, this paper provides different approaches and answers to the above issues.