The Weighted Average Cost of Capital (WACC) is a financial metric used to measure a company's cost of capital. It is the average rate of return that a company must pay to its investors to finance its assets. Companies use the WACC to determine the rate at which they should discount future cash flows when making investment decisions.

The WACC is calculated by taking the weighted average of the cost of each component of a company's capital structure, including both debt and equity. The cost of debt is typically the interest rate that the company pays on its debt, while the cost of equity is the return that shareholders expect for investing in the company. The weights assigned to each component are determined by the proportion of each type of capital in the company's capital structure.

For example, if a company has $50 million of debt and $50 million of equity, then the debt would have a weight of 50% and the equity would have a weight of 50%. If the cost of debt is 5% and the cost of equity is 10%, then the WACC would be the weighted average of these two costs, or 7.5%.

The WACC is an important metric for companies to consider when making investment decisions. A higher WACC means that the company must offer a higher rate of return to its investors, which can make certain investments less attractive. Conversely, a lower WACC can make certain investments more attractive.

The WACC is also an important metric for investors to consider when evaluating a company. A lower WACC can indicate that a company is well-managed and has a strong capital structure, which can make it a more attractive investment.

In conclusion, the Weighted Average Cost of Capital (WACC) is a key financial metric used to assess the cost of capital for a company. It is calculated by taking the weighted average of the cost of each component of a company's capital structure, and is an important metric for both companies and investors to consider when making investment decisions.