I have a correlation matrix that I produced in Excel using the monthly returns from 200 different trading systems over a X year period. So, the correlation matrix is 200 rows by 200 columns. How do I now go about determining the best combination of 10 systems that would give me the lowest correlated subset (i.e., lowest potential of aggregate sum of correlation values in a 10x10 correlation matrix)? Also, can this be done in Excel? Thanks.