# Calculating the Cost of Capital: Issues in Practice, Part 2

This post is the second part of our Calculating the cost of capital series

In our Primer, Level 1 and Level 2 Financial Modeling Courses, we teach students to use a variable Cost of Capital when building a valuation model of a company. The variability in the WACC and/or Cost of Equity (depending on the valuation technique) is largely influenced by the mix of Shareholders' Equity versus other more senior sources of Capital (eg. Debt, Convertible Notes, Preference Shares etc), which affects β (Beta) in the Cost of Equity Calculation. Focussing on the Cost of Equity, the other ways that it can vary are generally via a change in the Risk Free Rate or a change in the Market Risk Premium.

The most commonly used equation for determining the Cost of Equity is the Capital Asset Pricing Model (CAPM), which calculates the Cost of Equity as:

Ke = RFR + β X MRP

Where:

Ke = Cost of Equity

RFR = Risk Free Rate

β = Beta (levered)

We teach more about all the components of CAPM in our Primer and Level 1 Courses, but you can see that there are three inputs, and all these inputs can change. In particular β can change based on the Capital Structure of a company, which is often forecast to change substantially when modelling a company on a stand-alone or acquisition transaction basis over a forecast period.

So intiuitively if you understand the components of CAPM it makes sense to have a variable Cost of Equity (and WACC) if you are forecasting a variable Capital Structure (which is almost all the time). Lets run through a worked example to demonstrate quickly the consequence of using a fixed Cost of Equity versus a Variable Cost of Equity to value a set of cash flows produced by a company: The company in the example is drawing down additional debt each year which contributes to its Cash Flow to Equity, boosting the amount the company can pay its Equity Investors, but this comes at the cost of taking on additional Financial Leverage and the associated risks. However, our discount rate is determined at the start of the period (at 10%) when the Financial Leverage and associated risk is much lower.

Our terminal value in particular is affected by this assumption on the discount rate. In this example we have assumed no growth in cash flow after 2015, so the terminal value is simply calculated as the 2015 Cash Flow to Equity (125) divided by the Discount Rate in 2015 (10%). The question then is, would an investor be willing to accept the equivalent % returns for a cash flow subject to 100% Debt/Equity Leverage as seen in 2011, and for a cash flow subject to a 300% Debt/Equity leverage as seen in 2015. Answer: unlikely...

Lets look at the same cash flows and Leverage scenario, but with the Cost of Equity changing due to Beta increasing in line with the increase in Leverage (see our Primer and Level 1 Financial Modeling courses for specific equations on how to do this): You can see that the Terminal Value in 2015 is worth 234 less if the Cost of Equity is varied based on the higher leverage in 2015, and our overall valuation on the company falls from 1042 to 858 (-17.7%).

One of the key tenants of Financial Theory is that the greater the risk of an investment, the greater the returns required by the investor. As such the variable Cost of Equity Approach makes sense. So why wouldn't you use a variable Cost of Equity given it seems to value a company more effectively?