A model for the changes in some phenomena which can be classified in but one of three mutually exclusive and exhaustive classes with Markov dependence is proposed. Examples of such phenomena include: the change of the prices of the stocks and bonds in the stock – exchange, the change of the prices of some goods such as gold, silver, cotton, wheat, petroleum, ... , etc., in the international markets, the change of interest rates, the change of unemployment rates, and so forth. The direction of change may be positive (success), zero (no change or stability), or negative (failure). The proposed model has six parameters and . Asymptotic estimates of these parameters are obtained by using Maximum Likelihood and Newton-Raphson methods. An application for the change of the price of a given stock for a certain company is given. Kolmogorov-Smirnov test is used to test the congruence between the empirical and estimated distributions