We did a lot of tests trying to optimize Quanttrader strategies using the Sortino ratio, however the results have been very poor! The problem is that for the Sortino Ratio strong up-moves are just positive Events, which results in more buying of an asset. Because of the mean reversion however this is normally not a good strategy. A strong up-move is equally a risk and you better keep your allocation constant or even reduce it. using the sharp ratio works much better!