To estimate WACC for a startup, you need to determine its capital structure and cost of each source of capital. The capital structure is the mix of debt and equity that the startup uses to finance its operations. The cost of debt is the interest rate that the startup pays on its borrowings. The cost of equity is the return that the startup's shareholders expect from investing in it. The formula for WACC is: WACC = (D / V) x Rd x (1 - T) + (E / V) x Re where D is the amount of debt, E is the amount of equity, V is the total value of the startup, Rd is the cost of debt, Re is the cost of equity, and T is the tax rate.
Estimating the cost of equity for a startup can be challenging, because it may not have a market price or a beta, which measures the risk and volatility of its returns relative to the market. One way to estimate the cost of equity for a startup is to use the capital asset pricing model, or CAPM, which is: Re = Rf + Beta x (Rm - Rf) where Rf is the risk-free rate, Beta is the beta of the startup, and Rm is the market return. You can use the risk-free rate of a government bond or treasury bill as a proxy for Rf, and the historical return of a broad market index, such as the S&P 500, as a proxy for Rm. To estimate Beta, you can use the beta of a comparable publicly traded company in the same industry or sector as the startup, or adjust it based on the startup's growth rate, leverage, and size.