We provide a monotonic transformation of an initial diffusion with a level-dependent diffusion parameter that yields a second, deterministic parameter process. Altering the diffusion parameter while maintaining the original Brownian motion at the expense of the drift can be viewed as a...

Implications of factor-based asset pricing models for estimation of expecte d returns and for portfolio selection are investigated. In the presence of model mispricing due to a missing factor, the mispricing and the residual covariance matrix are linked together. Imposing a strong form of this...