The entire idea of valuing companies using a discounted cash flow method is based on the premise that the value of a company is the value of its future cash flows, discounted by an appropriate rate to the present.
Now, DCF models provide a very elegant solution to the valuation problem. Simply plug in your implied growth rate, your starting cash flow and tadah! You have the intrinsic value of a company.
However, what most people do not realise is that DCF faces several challenges that can potentially overvalue or undervalue a company.
The first challenge is that DCF is extremely imprecise. Put in garbage and you get garbage valuation. Its notoriously hard to predict whats going to happen the next year, much less 20 years into the future. I would be very suspicious of anyone claiming to be able to do so!
Secondly, if you look at a discounted cash flow model, it only shows results getting better year after year (entirely ridiculous!). There is never a down year. Furthermore, high growth rates are impossilbe to maintain over time due to the law of big numbers. For example, its a mathemtical impossilibty that Apple can keep growing at its current growth rate in the long run so it would be suicidal to use a DCF model here.
Finally, there is the problem of choosing an appropriate discount rate. Academics have debated it to the death and still no firm consensus has been ironed out. I have even seen people deriving a discount rate from beta (which I consider to be a ridiculous concept..) which makes no sense whatsoever to me.
That being said, I still feel that Discounted Cash Flows are still the best method in many situations to evaluate companies. It’s really a situation whereby there are a lack of better tools avaliable to do the job. In other to deal with the flaws of the DCF Model, I normally try to do the following:
1) DCF Valuation should be the last step of your entire evaluation process.
2) Look for a company with relatively stable free cash flow throughout a long number of years.
3) Be extremely conservative in your growth rates. If it looks to good to be true, it probably is. As a rule of thumb, companies that post growth rates exceeding 15% rarely meet expecations.
4) Look at the relative valuations like P/E to see if your valuation makes any sense.
The above discussion highlights why Margin of Safety is the most important aspect of investing. Valuation is really more art than science. Benjamin Graham once valued a company to be worth between $15 – 40 – reflecting how imprecise he knew it to be.
Always demand a Margin of Safety no matter what kind of valuation tool you use.
In the end, DCF is only one of the methods to go about valuing a company. My advise would be to look at different valuation methods to see where yours stands before making an investment decision.