本文以美國內線交易的案例為基礎，對2010-2017年由美國證監會所判決的訴訟書中的資料進行了分析，試圖延伸Guercio (2013)做的執法強度對於內部交易的影響。如預期所料，發現在宣告日當天的超額報酬會超過內線交易日的報酬。站在公司性質的角度，在執法強度與內線交易量或價格的呈現負相關的條件下，未計劃（併購）的公司宣告會比有計劃（盈餘）的公司宣告使這個效果更加強烈。此外，對於同等條件下的沒有選擇權交易的股票會比有選擇權交易的股票使這個效果突出。換句話說，內線交易者可以通過選擇有選擇權交易的公司去進行內線交易的活動，從而避開SEC的執法與監督。

Our study makes an analysis of the litigation adjudged by Securities and Exchange Commission (SEC) between 2010 and 2017 on the basis of American insider trading cases, which aims to extend the idea of Guercio (2013) regarding the impact of SEC’s level of enforcement on insider trading. As is expected, the study finds that the abnormal return on the announcement day would outweigh its insider trading day counterpart. With reference to the characteristic of the company and under the circumstance that SEC’s level of enforcement has a negative relationship with either the insider trading volume or the stock price, this relationship would seem stronger in unscheduled（M&A）announcement that that in scheduled (financial report)announcement. Besides, empirical results indicate that this relationship would be stronger for stock without trading stocks than stock that traded with options. In other words, insider traders can avoid SEC enforcement and supervision by buying stocks with traded options to conduct insider trading activities.

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