Finance School of Management Riskless asset a security that offers a perfectly predictable rate of return in terms of the unit of account selected for the analysis and the length of the investor 's decision horizon For example, if the U s dollars is taken as the unit of account and the decision horizon is half a year the riskless rate is the interest rate on U.s Treasury bills maturing after half a year uesTc11 Finance School of Management Riskless Asset ❖ A security that offers a perfectly predictable rate of return in terms of the unit of account selected for the analysis and the length of the investor’s decision horizon. – For example, if the U.S dollars is taken as the unit of account and the decision horizon is half a year, the riskless rate is the interest rate on U.S Treasury bills maturing after half a year