Weighted average cost of capital

What is the Weighted Average Cost of Capital?

The weighted average cost of capital (WACC) is a compilation of the aggregate financing costs of a business. In this calculation, each element of the firm’s financing cost is proportionately represented. All sources of capital are used in the calculation, including bonds, short-term and long-term notes, common stock, and preferred stock. The WACC is used to discount the cash flows associated with capital budgeting proposals to determine their net present values. The components of the cost of capital are common stock, preferred stock, and debt.

The WACC tends to decrease as a percentage when a business uses a higher proportion of debt as its source of funding, since the related interest expense is tax deductible, which reduces the cost of this form of funding. However, if too much debt is used, lenders will raise the interest rates charged, which increases the WACC. Consequently, there is a "sweet spot" where a business can take on an optimal amount of debt burden.

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Example of the Weighted Average Cost of Capital

The following table shows a derivation of the weighted average cost of capital, where the outstanding amount of each funding source is multiplied by its related cost, to arrive at an aggregate cost percentage for all sources of revenue. Note that the weighted average of the various elements of the cost of capital in the sample calculation is 12%, which would then be used for the analysis of proposed investments.

Inclusion of a Risk Premium

When evaluating an investment proposal, the net present value calculation should only use the WACC to discount the associated cash flows if the risk profile of the investment is approximately the same as that of the firm. If the investment is more risky, then a risk premium should be added to the WACC and then used as the discount rate.

Problems with the Weighted Average Cost of Capital

The main problem with the weighted average cost of capital is that the cost of equity can be difficult to calculate. It is derived from the rate of return for the general market, the beta value of the stock, and the current risk-free rate. All three of these values can vary somewhat by day, so the cost of equity can be considered a moving target.

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