1. A method for partitioning a plurality of investments into groups requiring use of a computer coupled to a database of investment data, wherein the computer is programmed to perform the method, the method comprising: calculating a measurement of similarity between each pair of investments; performing a mathematical conversion on the measurement of similarity such that these values are mapped into a range of positive values in which a lower positive value reflects a greater degree of similarity between the investments; and using such converted or mapped values to partition the investments into groups such that the similarity among the investments within each group is as high as possible and the similarity between the investments in a given one of the groups and the investments of every other group is as low as possible.