Chapter 05 – Risk and Return: Past and Prologue
16.
a. With 70% of his money in your fund’s portfolio, the client has an expected rate
of return of 14% per year and a standard deviation of 18.9% per year. If he
shifts that money to the passive portfolio (which has an expected rate of return
of 13% and standard deviation of 25%), his overall expected return and standard
deviation would become:
E(rC) = rf + 0.7 E(rM) – rf]
Therefore, the shift entails a decline in the mean from 14% to 11.2% and a decline
in the standard deviation from 18.9% to 17.5%. Since both mean return and
standard deviation fall, it is not yet clear whether the move is beneficial. The
disadvantage of the shift is apparent from the fact that, if your client is willing to
accept an expected return on his total portfolio of 11.2%, he can achieve that
return with a lower standard deviation using your fund portfolio rather than the
passive portfolio. To achieve a target mean of 11.2%, we first write the mean of
the complete portfolio as a function of the proportions invested in your fund
portfolio, y: