TY - JOUR AU - Myers,Stewart C. AU - Ruback,Richard S. TI - Discounting Rules for Risky Assets JF - National Bureau of Economic Research Working Paper Series VL - No. 2219 PY - 1987 Y2 - April 1987 UR - http://www.nber.org/papers/w2219 L1 - http://www.nber.org/papers/w2219.pdf N1 - Author contact info: Stewart C. Myers Massachusetts Institute of Technology Sloan School of Management E62-620 77 Massachusetts Avenue Cambridge, MA 02142 Tel: 617/253-6696 Fax: 617/258-6855 E-Mail: scmyers@mit.edu Richard S. Ruback Morgan Hall 495 Graduate School of Business Harvard University Soldiers Field Road Boston, MA 02163 Tel: 617/495-6422 E-Mail: rruback@hbs.edu AB - This paper develops a rule for calculating a discount rate to value risky projects. The rule assumes that asset risk can be measured by a single index (e.g., beta), but makes no other assumptions about specific forms of the asset pricing model. It treats all projects as combinations of two assets: Treasury bills and the market portfolio. We know how to value each of these assets under any theory of debt and taxes and under any assumption about the slope and intercept of the market line for equity securities. Our discount rate is a weighted average of the after-tax return on riskless debt and the expected return on the portfolio, where the weight on the market portfolio is beta. ER -