Dividends, Dividend Policy And Option Valuation: A New Perspective

This paper develops a model which explicitly incorporates the impact of the payment of dividends on the underlying stock into the valuation of both American and European calls and puts. Unlike earlier models, what we call the Dividend Adjustment Merton (DAM) model neither assumes arbitrary continuous dividends nor uses ad hoc methods to adjust for discrete dividend payments. Instead, it assumes the existence of a Miller and Modigliani (1961) valuation neutral dividend policy and adjusts Merton's constant proportional dividend model to incorporate any known schedule of discrete cash dividends of this type. The DAM model produces results which are equal to or superior to those of the separate models now used to value American calls (the Roll‐Geske‐Whaley model) and American puts (the Geske‐Johnson model) on dividend paying stocks. It has the virtue of being internally consistent in that the same model can be used to value both calls and puts. In developing the DAM model, the paper clarifies the role of dividends and dividend policy in determining option values. It also produces significantly tightened boundary conditions for option values.