bank stock, CAPM, ARMA, interest rates
The bank stocks equilibrium pricing relation is the traditional CAPM augmented by a second factor to account for the unexpected changes in the interest rates. This paper examines the methodological issue of constructing an interest rate variable that is orthogonal to the market index. We test a new approach in which the interest rate variable and the market return are treated as the components of a bivariate vector, a suitable vector ARMA model is determined, and then the appropriate whitened residuals are used as the interest rate factor in the two-factor model. Results are compared with the results from other models in which prevailing orthogonalization procedure is used. Our investigation indicates that the robustness of the result depends, to a limited extent, on the procedure employed to orthogonalize the two factors.