This is the beta of the fund relative to its Best Fit Index. Beta is a measure of a fund's sensitivity to market movements. The beta of the market is 1.00 by definition. Morningstar calculates beta by comparing a fund's excess return over Treasury bills to the Best Fit Index's excess return over Treasury bills. A beta of 1.10 shows that the fund has performed 10% better than its Best Fit Index in up markets and 10% worse in down markets, assuming all other factors remained constant. See also Best Fit Index, Beta.