We examine CEOs stock option exercises with respect to the use of the underlying shares (i.e. the sale or the holding) and with respect to the time left to expiry of stock options. We test whether the exercise decision is driven by option expiry, by private information or by liquidity and diversification needs. We find that in most cases, options are exercised before the last quarter preceding the expiry date, and for these options, CEOs exercise shortly after a stock price increase, which is consistent with the market timing hypothesis. We also find that stock options exercised close to expiry are not driven by private information and those exercised far from expiry are driven by private information about the future. CEOs hold the shares when they expect a positive stock performance over a long-term horizon and sell the shares when they expect a poor future performance.