The sensitivity analysis has shown that the DCF method is very vulnerable to changes in the underlying assumptions. Only marginally changes in the perpetual growth rate will lead to huge variances in the terminal value. Since the terminal value accounts for a large portion of the company’s value, this is of big significance for the validity of the DCF method.
It is very easy to manipulate the DCF analysis to result in the value that you want it to result in by adjusting the inputs. This is even possible without making changes that would be significant from an economist’s point of perspective, e.g. a change in the perpetual growth rate or in the WACC by just a few base points. Analysts or business professionals have no tools to estimate the input factors with that kind of exactness.
However, the DCF analysis is a great tool to analyze what assumptions and conditions have to be fulfilled in order to reach a certain company value. This is especially helpful in the case of capital budgeting and in the creation of feasibility plans.
The company valuation using discounted cash flows is a valid method to assess the company’s value if special precaution is put on the validity of the underlying assumptions. As with all other financial models, the validity of the DCF method almost completely depends on the quality and validity of the data that is used as input. If used wisely, the discounted cash flow valuation is a powerful tool to evaluate the values of a variety of assets and also to analyze the effects that different economic scenarios have on a company’s value.
The range of reasonable rates for discount factor and perpetual growth rate depends on each specific firm, its business situation and many more variables. In general you can say that the more risky a firm is, the higher its capital costs (WACC) are. The perpetual growth rate should be the same for all industries, since according to the arbitrage theory in the long run all companies and industries will grow by the same rate.