How to value employee stock options

One of the arguments often used against expensing employee stock options is that calculating their fair value at the time they are granted is very difficult. This article presents an approach to calculating the value of employee stock options that is practical, easy to implement, and theoretically sound. It explicitly considers the vesting period, the possibility that employees will leave the company during the life of the option, the inability of employees to trade their options, and the relevant dilution issues. This approach is an enhancement of the approach suggested by the Financial Accounting Standards Board's Statement of Financial Accounting Standards No. 123 because it does not require an arbitrary reduction in the life of the option to allow for early exercise caused by the inability of employees to trade their options.