This paper examines whether the adoption of stock option plans results in changes in shareholders’ wealth, and whether the stock market reactions to ESOP announcements could be explained by the target group of ESOP and the dilution effect. Short-horizon test methods are applied for this purpose. The sample consists of ESOP announcements of Finnish publicly quoted companies on the Helsinki Stock Exchange during the time period 1988–1998. The event study results show a slightly positive market reaction to announcements of ESOPs targeted to management and a negative market reaction in the case of ESOPs targeted to all employees. The results of regression analysis show that the ESOPs with limited dilution convey positive information to the stock market and the dilution effect has a negative impact on stock returns, especially in the case of ESOPs targeted to all employees.