DCF (Discounted Cash Flow) Basics

What is DCF?

DCF (Discounted Cash Flow) is a valuation method that sums up all future cash flows a company is expected to generate, but discounts them to reflect that money in the future is worth less than money today. While methods like the P/E ratio or P/B ratio rely on relative comparisons with other companies, DCF is closer to an absolute valuation, calculating a company's value based solely on the cash it is expected to generate.

The core premise is simple: $1,000,000 today is not the same as $1,000,000 a year from now. This is because the purchasing power of money decreases over time due to inflation and opportunity costs. DCF translates this time value of money into a formula, and this article serves as an educational explanation to understand its principles.

Discount Rate and Present Value Calculation

The discount rate is the tool used to convert future cash into present value. If the discount rate is r and the number of years is n, the present value of a cash flow n years from now is calculated as 'Future Cash Flow ÷ (1+r)^n'. For example, if the discount rate is 10%, the present value of $1,100,000 one year from now is $1,100,000 ÷ 1.1 = $1,000,000, and $1,210,000 two years from now is $1,210,000 ÷ 1.21 = $1,000,000.

In corporate valuation, the Weighted Average Cost of Capital (WACC) is typically used as the discount rate. WACC is a weighted average of the return required by shareholders and the interest rate on debt, based on their respective proportions in the capital structure. A higher discount rate sharply reduces the present value of distant future cash flows, meaning that a single assumption about the discount rate can significantly alter the results.

DCF typically involves individually discounting cash flows for a predictable period of 5 to 10 years. Cash flows beyond this period are then grouped together and calculated as a terminal value using a 'perpetual growth model'. Since terminal value often accounts for more than half of the total value, the assumption made for the terminal period has a significant impact.

Calculation with a Simple Example

Let's assume a company consistently generates $10 billion in Free Cash Flow (FCF) annually, with a discount rate of 10% and a perpetual growth rate of 2%. The value of growing perpetual cash flows is calculated as 'FCF × (1+Growth Rate) ÷ (Discount Rate − Growth Rate)', which yields $10 billion × 1.02 ÷ (0.10 − 0.02) = approximately $127.5 billion.

If net debt (borrowings minus cash) is $27.5 billion, then the value attributable to shareholders is $127.5 billion − $27.5 billion = $100 billion. If there are 1,000,000 shares outstanding, the intrinsic value per share is estimated to be approximately $100. If the current share price is $70, it could be interpreted as undervalued by this calculation; if it's $130, it could be seen as overvalued.

However, these numbers are only meaningful if the input assumptions are accurate. Even a slight reduction in the discount rate by just one percentage point, from 10% to 9%, would decrease the denominator from 0.08 to 0.07, causing the value to jump by approximately 14%. It's important to remember that small changes in assumptions can significantly alter the results.

How to Use in Practice

DCF is best used not as a tool to produce a single correct answer, but as a framework for organizing thought. By dividing scenarios into conservative, neutral, and optimistic, and calculating the intrinsic value for each, one can then reverse-engineer to see which scenario the current stock price reflects, thereby gauging market expectations.

DCF is relatively well-suited for companies with stable and predictable cash flows, such as those in industries with low revenue volatility like telecommunications, utilities, or consumer staples. Conversely, for early-stage growth companies that are unprofitable or frequently change their business models, estimating future cash flows is difficult, making DCF alone less reliable.

Therefore, in practice, DCF is used to establish an absolute valuation, and this is cross-checked with relative metrics like P/E ratio and EV/EBITDA. Combining methods so that the weaknesses of one are compensated by the strengths of another is a common approach in both the Korean and US markets.

Pitfalls and Limitations

The biggest weakness of DCF is its sensitivity to input values. Even slight changes in assumptions for the discount rate, growth rate, or terminal value can cause results to fluctuate significantly. This means that by adjusting assumptions to fit a desired conclusion, almost any stock price can be justified. A sophisticated formula does not guarantee the accuracy of the conclusion.

Furthermore, the perpetual growth rate cannot exceed the long-term economic growth rate. No company can grow faster than the overall economy indefinitely, so it is reasonable to keep the perpetual growth rate within a conservative range, such as 2-3%. Artificially inflating this rate will unrealistically inflate the terminal value.

Ultimately, the value of DCF lies not in providing a precise number, but in revealing what assumptions are embedded in the current stock price. This article is an educational resource for understanding valuation principles, not an investment recommendation.

Key Checkpoints

First, DCF is an absolute valuation method that discounts future cash flows to their present value and sums them up. Second, assumptions for the discount rate and perpetual growth rate dictate the results, so a wide range of scenarios should be considered. Third, remember that terminal value often accounts for a significant portion of the total value, and DCF is best suited for companies with stable cash flows.

Rather than blindly trusting a single number, it is safer to consider a range of assumptions and cross-verify with relative metrics. A model is most useful when used as a tool to organize questions, not to provide definitive answers.