Talk:Modigliani risk-adjusted performance

formula differences
From a quick back of the envelope calculation it does not look like $$M^2\equiv\overline{R_C}-\overline{R_M} = (\overline{R_P} -\overline{R_f})\frac {\sigma_M}{\sigma_P}-(\overline{R_M} -\overline{R_f})$$ and $$M^2 \equiv S \times \sigma_B - \overline{R_M}$$ are equivalent. For the two equations to both give $$M^2$$ then $$\sigma_B = \frac{\overline{R_f} \sigma_P}{\overline{R_P} - \overline{R_f}} + \sigma_M$$. Does anyone have citations for both of these to be the same or both being used as the Modigliani risk-adjusted performance? If they aren't the same, which is more widely considered the right choice? Zfeinst (talk) 14:56, 3 August 2012 (UTC)