Problem Set 4
1. Describe what happens to the total risk of a portfolio as the number of securities is increased. Differentiate between systematic risk and unsystematic risk and explain how total risk and systematic risk are measured.
As the number of securities increases, the total risk of the portfolio decreases. This decrease occurs due to the benefits of diversification which is the process of acquiring a portfolio of securities that have dissimilar risk-return characteristics in order to reduce overall portfolio risk. The total risk of a security or a portfolio is measured with the variance or standard deviations of returns (std dev. ^2 = variance). The larger the standard deviation, the greater the total risk and the more likely it is that you will have a large price move.
Unsystematic risk is the unique or security specific risks that tend to partially offset one another in a portfolio. /this could happen when the price of one stock in the portfolio goes down, the price of another tends to go up, which partially offsets the loss. As long as the returns of two securities are not perfectly, positively correlated, one can reduce total risk by combining securities in a portfolio. By adding securities to a portfolio, it is possible to eliminate unsystematic risk.
Systematic risk is also known as market risk or nondiversifiable risk. The risk tends to affect the entire market in a similar fashion. Systematic risk cannot be diversifies away because it is cause by general market movements that tend to affect all stocks similarly. Systematic risk is measured by how closely a security’s returns are correlated with the returns of the entire market. Beta measures a stock’s returns in relation to general market swings. Stocks with betas greater than 1 are referred to as aggressive stocks because they carry greater systematic risk than the market. An example of this would be if a stock had a beta of 2 while the market has a beta