Reflects the percentage of a fund's movements that are explained by movements in its bench mark index. An R-Squared of 1 means that all movements of a fund are completely explained by movements in the index. For example, index funds that invest only in S&P 500 stocks will have an R-squared very close to 1. Conversely, a low R-Squared indicates that very few of the fund's movements are explained by movements in its bench mark index. An R-Squared measure of .35, for example, means that only 35% of the fund's movements can be explained by movements in its bench mark index.