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Sortino Ratio

The Sortino ratio measures return per unit of downside risk, counting only losses as risk. It's a refinement of the Sharpe ratio that doesn't penalise a fund for big positive swings.

sortino = (mean(r_m - rf_m) / downside_dev) * sqrt(12), where downside_dev = sqrt(mean(max(rf_m - r_m, 0)^2))

What the Sortino ratio tells you

The Sharpe ratio treats all volatility as bad — even months where the fund jumped up. Most investors don't mind upside surprises; they fear losses. The Sortino ratio addresses this by measuring return only against downside deviation (the volatility of negative returns).

How to read it

How FindMF computes it

From AMFI NAVs we build a month-end return series over completed months. We subtract the monthly risk-free rate (0.07/12), then divide the mean excess return by the downside deviation — the root-mean-square of months where the fund fell short of the risk-free rate — and annualise by sqrt(12). A minimum of 12 months is required, otherwise the metric is suppressed. See methodology; FindMF takes no commission.

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