What is the impact of changes in the flow of dividends on the valuation of common stock? How should you approach the valuation of common stock that does not pay dividends? 2.Efficient portfolio theory. What is the meaning of efficient portfolio as described by the Modern Portfolio Theory? What type of risk cannot be diversified, and why? 3.Approaches to cost of capital calculations. What are the weaknesses of the WACC and MWACC calculations?