This study explores the impact of anti-fugitive offenders’ draft amendments to the “Prohibition of Masking Regulations” of Hong Kong on whether abnormal returns exist with Taiwanese firms holding significant investment activities in mainland China. This study utilizes the methodology of event study to analyze the average and cumulative abnormal returns on 28 sample firms from Taiwan. The results show that there is no significant response for average cumulative abnormal return before the event day. However, significant responses exist on the second, ninth and fifteenth day after the event, indicating that positive response of stock prices could not be satisfied at one time. Which also shows that Chinese concept stocks does not react significantly to the event in question.