Share repurchases have gradually become firms' important economic activities after the stock repurchase deregulation in Taiwan in 2000. However, few researchers have explored the influence of completion rates on the stock market, and whether managers have dual timing abilities for both repurchase announcements and actual repurchases. This study investigates the market reactions to actual repurchase activities, and managerial timing abilities. Through the t-test and the regression analysis, the results are as follows: 1. Repurchase programs have significantly positive influences on stock prices both to the listed and the OTC firms after the share repurchase announcements; 2. Abnormal returns during the repurchase period are negatively related to completion rates; 3. Completion rates are negatively associated with abnormal returns after the actual repurchase announcements; 4. The abnormal returns of firms that do actual repurchases early are higher than those of firms that do actual repurchases late after the completion period. These results can provide information about managerial decision making in practice, and suggest legislators take firms' strategic trading behavior into consideration while assessing the effects of the legislation about share repurchases.