The article reviews different models used to understand how the risk of an investment affects its expected return. The traditional model, CAPM, only considers one factor (market return), but newer models like the Fama and French three-factor model and Carhart four-factor model include additional factors like size and value. The Fama and French five-factor model adds profitability and investment patterns to better explain stock returns. These models help academics, financial analysts, and researchers understand how different factors influence asset pricing.