Markowitz's main contribution to portfolio theory is: that risk is a function of credit, liquidity and market factors insight about the relative importance of variance and covariance in determining portfolio risk risk is not quantifiable that risk is the same for each type of financial asset Given the following expectations for return, risk and correlation: E (r) o psb Portfolio S 0.22 0.31 -0.25 Portfolio B 0.1 0.06 Risk-free 0.055 An optimal portfolio of S and B has been calculated to contain 0.5 stocks, i.e. portfolio S (out of a possible 100% or 1.0). What would be the standard deviation of the optimal portfolio from S and B? 0.1590 0.1503 0.1639 0.1706 0.1774 Given the returns, risk, and correlation: E (r) O pSB Portfolio S 0.16 0.42 -0.17 Portfolio B 0.085 0.21 Risk-free 0.045 What is the weight of Portfolio S for the minimum-variance portfolio? 0.2643 0.2359 0.2274 0.2465 0.2550