Sortino Ratio

What Does Sortino Ratio Mean?
A ratio developed by Frank A. Sortino to differentiate between good and bad volatility in the Sharpe ratio. This differentiation of upwards and downwards volatility allows the calculation to provide a risk-adjusted measure of a security or fund's performance without penalizing it for upward price changes. It it is calculated as follows:

Investopedia explains Sortino Ratio
The Sortino ratio is similar to the Sharpe ratio, except it uses downside deviation for the denominator instead of standard deviation, the use of which doesn't discriminate between up and down volatility.