What is likely to happen to a company's Weighted Average Cost of Capital (WACC) as more debt is added, initially?

As more debt is added to a company's capital structure, the Weighted Average Cost of Capital (WACC) is likely to decrease initially because debt financing is typically less expensive than equity financing. This is primarily due to the tax deductibility of interest payments, which lowers the effective cost of debt.

When a company takes on debt, it can use this less expensive source of financing to fund projects or investments, which can lead to a lower overall WACC up to a certain point or optimal level of debt. At this optimal level, the benefits of taking on additional debt (such as tax shields) are maximized, and the cost of equity may start to rise due to increased financial risk perceived by equity investors. Therefore, the WACC decreases initially with the addition of debt until this optimal point is reached, after which it may start to increase again if further debt is added beyond that level. This behavior of WACC concerning the capital structure demonstrates the balance between the benefits and risks of leveraging debt in financing decisions.