The Capital Asset Pricing Model (CAPM), an equilibrium model for the price determination of risky assets, was developed by Sharpe [16], Lintner [9, 10] and Treynor [21], following the pioneering work of Markowitz [12, 13] and Tobin [20]. In spite of the tremendous impact of this model on the profession, the CAPM still raises many questions, and is inconsistent with a considerable body of empirical evidence.

Two measures of investment worth: the discounted-rate-of-return and the payback method will be compared here. Many examples can be found in the literature illustrating the serious limitations of the payback method.According to these examples, an investment proposal may be judged economically undesirable when in actual fact it is highly profitable. This happens when the annual cash flow is not equal, and the investment project promises a relatively large cash flow after the cut-off period.

Market returns, Accounting returns, Variability of earnings