Figure 2 illustrates the reduction of total risk as securities are added to a portfolio.Unsystematic risk is virtually eliminated in portfolios of 30 or 40 securities drawnfrom industries that are not closely related. Because the remaining systematic risk is market related,diversified portfolios tend to move in tandem with the market.The popular market indices (the Dow Jones Industrial Average, the S-P 500,and the New York Stock Exchange Index, for instance) are themselves diversified portfolios and tend to move in parallel.Thus, there is a close corredpondence between swings in the returns of any diversified portfolio and in the returns on market indices such as the Dow.Examples of systematic and unsystematic risk factors are listed in Table B.