4. Consider a portfolio consisting of an equal number of shares of the companies listed in ChinaStock.mat. The price of the portfolio is the average price of the companies. And the accumulative return of the portfolio in period (T1, T2] is written as: Rr = ln(Pportfolio, T/Pportfolio, T) where Pportfolio is the portfolio price. Use Matlab to answer the following questions: (a) Find the accumulative return of the portfolio in the one-year period. (b) Suppose that the portfolio holder has the option to sell the portfolio at the end of each week during the year. Find the maximal accumulative return and the corresponding week to sell the portfolio. 4. Consider a portfolio consisting of an equal number of shares of the companies listed in ChinaStock.mat. The price of the portfolio is the average price of the companies. And the accumulative return of the portfolio in period (T1, T2] is written as: Rr = ln(Pportfolio, T/Pportfolio, T) where Pportfolio is the portfolio price. Use Matlab to answer the following questions: (a) Find the accumulative return of the portfolio in the one-year period. (b) Suppose that the portfolio holder has the option to sell the portfolio at the end of each week during the year. Find the maximal accumulative return and the corresponding week to sell the portfolio