Stock A $($with an expected return of $15\%$ and a beta of $1\mathrm{.}1)$ and stock B $($with an expected return of $20\%$ and beta $1\mathrm{.}6)$ are correctly priced. By how much is stock C under$-$priced $($expressed in terms of excess return relative to the SML$),$ if it has a beta of $1$ and expected return of $16\%?$