Shortfall risk refers to the probability that a portfolio will not exceed the minimum return level (target return; benchmark return). Shortfall-risk is more consistent with the investors’ intuitive perception of risk in that it focusses more on the real economic risk of an investor. On the other hand, the standard deviation is rather a measure of the volatility of financial assets. Shortfall risk is also known as downside risk.

The following diagram illustrates shortfall risk. As we can see, it is the risk that the portfolio value will fall below some minimum acceptable level, RL.