求助 finance 問題 只有一題

Compare the Sharpe Ratio for one of your portfolios with an expected return above the minimum variance portfolio. What can you say about the dierence between the portfolio Sharpe Ratio and the Sharp Ratio on the individual stocks? Explain why they
are different.

	ACT	GAS	VZ	PPL	ZION	ADSK	FFIV
mon mean	0.0342	0.0143	0.0142	0.0066	0.0277	0.0246	0.0368
annual mean	0.4103	0.1721	0.1706	0.0795	0.3318	0.2957	0.4417
monthly sd	0.0571	0.0412	0.0488	0.0450	0.1308	0.1022	0.1311
annual sd	0.1980	0.1429	0.1691	0.1560	0.4532	0.3539	0.4541
Sharp ratio	2.0729	1.2046	1.0088	0.5096	0.7322	0.8354	0.9727
					Rf	1.00%
					Rm	6%

I already get all sharp ratio of stocks, please help me with the short answer part.
Thanks alot.

The Sharpe Ratiio is defined as  (R-Rf)/STD(R), where R denotes the return for an individual stock, Rf means the risk free rate and  STD(R) is the standard deviation for the return of an individual stock. The porfolio version Sharpe Ratiio can be defined in a similar way. To calculate the return and the standard deviation of the return for the porfolio, you need to specify the weighting for each individual  stock and the co-variance matrix for the individual stocks should also be given.
Would you please honor your commitment and pay me 150 coins for the first answer?

The portfolio Sharpe Ratio should be higher than the the Sharp Ratio on an individual stock because of the diversification effect.

Thanks for the answer.
I have another question here, I know how to calculate for individual Sharpe Ratio, how to calculate the portfolio Sharpe Ratio?