How Do I Use the CAPM to Determine Cost of Equity?

What Is the Capital Asset Pricing Model (CAPM)?

In capital budgeting, corporate accountants and financial analysts often use the capital asset pricing model (CAPM) to estimate the cost of shareholder equity. Described as the relationship between systematic risk and expected return for assets, CAPM is widely used for the pricing of risky securities, generating expected returns for assets given the associated risk, and calculating costs of capital.

Key Takeaways

  • The capital asset pricing model (CAPM) is used to calculate expected returns given the cost of capital and risk of assets.
  • The CAPM formula requires the rate of return for the general market, the beta value of the stock, and the risk-free rate.
  • The weighted average cost of capital (WACC) is calculated with the firm's cost of debt and cost of equity—which can be calculated via the CAPM.
  • There are limitations to the CAPM, such as agreeing on the rate of return and which one to use and making various assumptions.
  • There are online calculators for determining the cost of equity, but calculating the formula by hand or by using Excel is a relatively simple exercise.

Cost of Equity CAPM Formula

The CAPM formula requires only the following three pieces of information: the rate of return for the general market, the beta value of the stock in question, and the risk-free rate.

CAPM Formula

Cost of Equity = Risk-Free Rate of Return + Beta * (Market Rate of Return - Risk-Free Rate of Return)

The no risk-free rate of return is the theoretical return of an investment with z

What the CAPM Can Tell You

The cost of equity is an integral part of the weighted average cost of capital (WACC). WACC is widely used to determine the total anticipated cost of all capital under different financing plans. WACC is often used in an effort to find the most cost-effective mix of debt and equity financing.

Assume Company ABC trades on the S&P 500 with a rate of return of 10%. The company's stock is slightly more volatile than the market with a beta of 1.2. The risk-free rate based on the three-month T-bill is 4.5%.

Based on this information, the cost of the company's equity financing is 11%:

Cost of Equity = 4.5% + (1.2 * (10% - 4.5%))

Numerous online calculators can determine the CAPM cost of equity, but calculating the formula by hand or by using Microsoft Excel is a relatively simple exercise.

The Difference Between CAPM and WACC

The CAPM is a formula for calculating cost of equity. The cost of equity is part of the equation used for calculating the WACC. The WACC is the firm's cost of capital which includes the cost of the cost of equity and cost of debt.

WACC Formula

WACC = [Cost of Equity * Percent of Firm's Capital in Equity] + [Cost of Debt * Percent of Firm's Capital in Debt * (1 - Tax Rate)]

WACC can be used as a hurdle rate against which to evaluate future funding sources. WACC can be used to discount cash flows with capital projects to determine net present value. A company's WACC will be higher if its stock is volatile or seen as riskier as investors will demand greater returns to compensate for additional risk.

Limitations of Using CAPM

There are some limitations to the CAPM, such as agreeing on the rate of return and which one to use. Beyond that, there’s also the market return, which assumes positive returns, while also using historical data. This includes the beta, which is only available for publicly traded companies. The beta also only calculates systematic risk, which doesn’t account for the risk companies face in various markets.

There are also various assumptions that must be made including that investors can borrow money without limitations at the risk-free rate. The CAPM also assumes that no transaction fees occur, investors own a portfolio of assets, and investors are only interested in the rate of return for a single period—all of which are not always true.

Is CAPM the Same As Cost of Equity?

CAPM is a formula used to calculate the cost of equity—the rate of return a company pays to equity investors. For companies that pay dividends, the dividend capitalization model can be used to calculate the cost of equity.

How Do You Calculate Cost of Equity Using CAPM?

The CAPM formula can be used to calculate the cost of equity, where the formula used is:


Cost of Equity = Risk-Free Rate of Return + Beta * (Market Rate of Return - Risk-Free Rate of Return)

What Are Some Potential Problems When Estimating the Cost of Equity?

The biggest issues when estimating the cost of equity include measuring the market risk premium, finding appropriate beta information, and using short- or long-term rates for the risk-free rate.

How Are CAPM and WACC Related?

WACC is the total cost cost of all capital. CAPM is used to determine the estimated cost of the shareholder equity. The cost of equity calculated from the CAPM can be added to the cost of debt to calculate the WACC.

The Bottom Line

For accountants and analysts, CAPM is a tried-and-true methodology for estimating the cost of shareholder equity. The model quantifies the relationship between systematic risk and expected return for assets and is applicable to a multitude of accounting and financial contexts.

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