Sunday, July 25, 2010


Risk Adjusted Discount Rate

For a long time, economic theorists have assumed that, to allow for risk, the businessman required a premium over and above an alternative, which was risk-free. Accordingly, the more uncertain the returns in the future, the grater the risk and grater the premium required. Based on this reasoning, it is proposed that the risk premium be incorporated into the capital budgeting analysis through the discount rate. That is, if the time preference for money is to be recognized by discounting estimated future cash flows, at some risk free rate, to their present value, then, to allow for the riskiness, of those future cash flows a risk premium rate may be added to risk-free discount rate. Such a composite discount rate, called the risk-adjusted discount rate, will allow for both time preference and risk preference and will be a sum of the risk-free rate and risk-premium rate reflecting the investors’ attitude towards risk. The risk-adjusted discount rate method can be formally expressed as follows:

Risk-adjusted discount rate = Risk free rate + Risk premium

Under capital asset pricing model, the risk premium is the difference between the market rate of return and the risk free rate multiplied by the beta of the project.

The risk adjusted discount rate accounts for risk by varying the discount rate depending on the degree of risk of investment projects. A higher rate will be used for riskier projects and a lower rate for less risky projects. The net present value will decrease with increasing risk adjusted rate, indicating that the riskier a project is perceived, the less likely it will be accepted. If the risk free rate is assumed to be 10%, some rate would be added to it, say 5%, as compensation for the risk of the investment, and the composite 15% rate would be used to discount the cash flows.

Advantages of risk adjusted discount rate
  • It is simple and can be easily understood.
  • It has a great deal of intuitive appeal for risk-averse businessman.
  • It incorporates an attitude towards uncertainty.


This approach, however, suffers from the following limitations:

  • There is no easy way deriving a risk adjusted discount rate. Capital asset pricing model provides a basis of calculating the risk adjusted discount rate. Its use has yet to pick up in practice.
  • It does not make any risk adjusted in the numerator for the cash flows that are forecast over the future years.
  • It is based on the assumption that investor are risk-averse. Through it is generally true, there exists a category of risk seekers who do not demand premium for assuming risks; they are willing to pay premium to take risks. Accordingly, the composite discount rate would be reduced, not increased, as the level of risk increases.

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