The Inter-Temporal Exercise and Valuation of Employee Options

We propose a multi-period model to value employee options allowing for the possibility that a risk-averse employee strategically exercises her options over time rather than at a single date. Our results describing the representative employee's option exercise behavior are broadly consistent with existing empirical evidence. The value of options to the employee and their effective cost to the firm are significantly different from the predictions of a constrained model that assumes single date strategic option exercise. The constrained model substantially underestimates the cost of options to the firm when, ceteris paribus, the employee's relative risk aversion and/or the time to maturity and/or the stock volatility exceed respective thresholds. Hence, the incorporation of multiple-date exercise has important economic and accounting consequences