The curriculum discusses the Market Model. The market model does include the Rf rate as a stand alone factor. The curriculum then introduces three formulas based on this model: a return formula, a variance formula and a covariance formula. First question: was the market model instrumental in developing the CAPM? In other words: why is CFAI spending time discussing this model? How does this fit in with the rest of the curriculum? Second question: can the formulas for variance and covariance be used in the context of the CAPM?