Probability weighting is one of the cornerstones of decision-making theories accommodating gambling preferences. This paper examines its relevance to explaining employee stock option exercise behavior. We characterized the optimal exercise policy for a representative employee with Rank-Dependent Expected Utility (RDEU) preferences. We find that the RDEU framework leads to improved predictions of empirical exercise patterns. The implications from our findings are twofold: (1) probability weighting implies an increase in stock option cost to shareholders; (2) employee exercise behavior-implied sentiment is affected by the firm's stock market risk and performance.