The subjective and objective evaluation of incentive stock options

Owners of incentive options invariably hold undiversified portfolios. This paper derives a model for the subjective and objective values of such options. The subjective value - the value to the holder - is less than the market value because the option is held in an undiversified portfolio and because it is exercised suboptimally from the market perspective. The objective value is the cost to the firm of issuing the option and lies between the market and subjective values. This value recognizes the suboptimal exercise but not the undiversified discount. The model, which is the Black-Scholes model with modified parameters, is simple to use.