The Capital Asset Pricing Model, or CAPM, is a financial calculation model used in investing to measure the relationship between an investor’s expected return a

The Capital Asset Pricing Model, or CAPM, is a financial calculation model used in investing to measure the relationship between an investor’s expected return and investment risk. CAPM was introduced in the 1960s by the renowned economist and scholar William F. Sharpe in his book *Portfolio Theory and Capital Markets*. The CAPM calculation adds the risk-free return to the risk premium. The resulting value represents the investor’s expected return. In the calculation, the most important factor is the β coefficient, also known as the systematic risk coefficient. Systematic risk refers to the inherent risk of the overall securities market, rather than the risk of a specific industry. It is affected by factors such as national interest rates, economic expansion or recession, and war. It is a type of risk that investors cannot reduce through portfolio diversification. By contrast, unsystematic risk refers to risks within a specific industry or company, usually caused by events such as industry strikes, raw material shortages, or poor company management. The CAPM value is often used to calculate financial metrics such as weighted average cost of capital (WACC) and discounted future cash flows. Rrf stands for Risk-Free Rate, which means the zero-risk rate of return. The risk-free rate usually matches the government bond yield of the country where the investment is made, and the bond maturity should also correspond to the investment horizon. In practice, the 10-year government bond yield is often used as the risk-free rate because 10-year government bonds are typically the most widely quoted and most liquid type of bond. In the United States, the 10-year Treasury yield is also used as the risk-free rate; the current 10-year Treasury yield is 2.74% [source]. Rm stands for Expected Return of the Market, which refers to the market’s expected rate of return. In the U.S. investment market, the average return of the S&P 500 is usually used as the expected market return. Based on the historical return of the S&P 500, its average return fluctuates around 10%, so 10% is typically selected as the expected market return. (Rm – Rrf) is called the risk premium, or Market Risk Premium. It refers to the extra return investors require above the risk-free rate as compensation for investing in risky assets. The greater a stock’s volatility, the higher its investment risk, the higher the investor’s expected return, and therefore the higher the risk premium. The β coefficient is a stock’s systematic risk relative to the overall stock market. It is calculated from historical stock returns using a specific method and measures the sensitivity of a stock’s risk to overall market movements. Its meaning is as follows: β < 0: a stock’s investment risk is negatively correlated with market movements; β = 0: a stock’s investment risk is not affected by market movements; 0 < β < 1: a stock’s investment risk is positively related to market movements, but with lower sensitivity; β = 1: a stock’s investment risk moves in line with market fluctuations; β > 1: a stock’s investment risk is highly sensitive to market movements. The β coefficient can also indicate an investor’s expected return on a stock: the higher the β value, the higher the investor’s expected return. ## How do you calculate Apple’s CAPM? This section uses Apple’s data as an example. The current yield on the U.S. 10-year Treasury is 2.74%, so Rrf = 2.74%. Data source The average return of the S&P 500 is 10%, so Rm = 10%. Apple’s current beta can be obtained from Barron’s: β = 1.22. So, Re = Rrf + β(Rm – Rrf) = 2.74% + 1.22(10% – 2.74%) = 11.60% Therefore, Apple’s current CAPM value is 11.6%. **What is the practical investment significance of the Capital Asset Pricing Model (CAPM)?** In the financial industry, CAPM is used in a variety of calculations, including the weighted average cost of capital (WACC) and discounted cash flow (DCF) valuation. WACC measures a company’s financing cost. When CAPM is used in WACC, it serves as the cost of equity, Re, in the formula: **WACC = (E/V × Re) + (D/V × Rd × (1 − Tc))** CAPM affects the cost of equity in the formula. The higher the CAPM value, the higher the company’s cost of raising funds through issuing stock, and therefore the higher the final WACC. When investors calculate the present value of a shareholder’s future cash flows, CAPM is used as the discount rate, that is, the “r” in the DCF formula. When the CAPM value is higher, the DCF value is lower, which means that as the investment horizon lengthens, future returns are worth less in today’s terms. The DCF formula is as follows: **DCFn = CF(1 + p)1 / (1 + r)1 + CF(1 + p)2 / (1 + r)2 + CF(1 + p)3 / (1 + r)3 + … + CF(1 + p)n / (1 + r)n** Here, **CF** stands for future cash flow, and **p** is the company’s cash flow growth rate. --- **What are the limitations of CAPM?** The main limitation of CAPM is the uncertainty in its inputs. The risk-free rate and expected market return are both based on averages, so it is difficult to produce a highly accurate estimate for a specific point in time. In practice, the risk-free rate may differ significantly from the current 10-year Treasury yield, or the expected market return may differ significantly from the current S&P 500 return, which can lead to valuation errors. Beta also has a certain margin of error. Because beta is calculated from historical stock returns, and stock prices tend to be highly volatile and difficult to follow a consistent pattern, it is hard to use beta to calculate a CAPM value that is both accurate and appropriate. Second, CAPM considers non-systematic risk in a limited way and does not account for industry-specific risks or company-specific risk characteristics. As a result, CAPM is more suitable for evaluating the impact of market risk on an investment, but it cannot further assess how a specific company’s business model affects investment returns.