This document discusses risk and rates of return in investments. It defines key concepts like stand-alone risk, portfolio risk, standard deviation as a measure of risk, beta as a measure of market risk, and the Capital Asset Pricing Model. Standard deviation and beta are calculated for sample investments like Treasury bills, a stock called HT, and a stock called Coll. Diversification benefits of portfolios are shown through lower standard deviation when combining unrelated stocks. The document also illustrates the security market line from the CAPM model and how beta relates a stock's risk to the overall market rate of return.