The relationship between risk and an expected return of an investment lays in the capital asset pricing model (CAPM). The main objective is to capitalize on the valuation of future benefits. The CAPM will thus provide insight into the appropriate rate of return of an asset for better decision making. CAPM ensures a relatively accurate prediction of the risks and yield. This paper aims to demonstrate the use of this model to major companies such as Google, Ford, BP, Microsoft, and Coca-Cola. This study will also demonstrate the correlation to the Modern Portfolio Theory. The Modern Portfolio Theory (MPT), or mean-variance optimization is a mathematical model used for assembling a portfolio of assets to maximize the expected return for such level of risks called variance. The key importance is that an asset's risk and return should not be assessed by itself, but by how it contributes to a portfolio's overall risk and return.