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The market portfolio is assumed to be composed of four securities. Their covaria

ID: 2708460 • Letter: T

Question

The market portfolio is assumed to be composed of four securities. Their covariance with the market and their proportions follow.

Security       Covariance with Market         Proportion

     A              242                            .2

     B              360                            .3

     C              155                            .2

     D              210                            .3

Given these data, calculate the market portfolio

The market portfolio is assumed to be composed of four securities. Their covariance with the market and their proportions follow. Given these data, calculate the market portfolio's standard deviation.

Explanation / Answer

Recall that the standard deviation of the market portfolio is equal to

square root of a weighted average of the covariance of all securities

with it, where the weights are equal to the proportions of the

respective securities in the market portfolio, in this case:


STD_M = sqrt(pA*cov_A + pB*cov_B + pC*cov_C + pD*cov_D) =

= sqrt(0.2*242 + 0.3*360 + 0.2*155 + 0.3*210) =

= sqrt(250.4) =

= 15.82


The market porfolio's standard deviation is 15.82