Theoretical Flaws in the Use of the CAPM For Investment Decisions

This paper uses counterexamples and simple formalization to show that the standard CAPM-based Net Present Value may not be used for investment valuations. The reason is that the standard CAPM-based capital budgeting criterion implies a notion of value which does not comply with the principle of additivity. Framing effects arise in decisions so that different descriptions of the same problem lead to different choices. As a result, the CAPM-based NPV as a tool for valuing projects and making investment decisions is theoretically unsound, even if the CAPM assumptions are met.