This tool does not correctly handle stock splits and thus all the correlations it produces are wrong for any stock that has ever had a split or a reverse split.

This tool does not correctly handle stock splits and thus all the correlations it produces are wrong for any stock that has ever had a split or a reverse split. It shows a split as a huge price drop, but that is not really how that works, since the number of shares expands, thus anyone holding the stock does not, in fact, face a 4x loss for a 1:4 split.