Mutual funds of all kinds are finding it tough to maintain their highest rankings for long, according to the Standard & Poor's semi-annual scorecard of mutual fund performance. S&P found that over three consecutive 12-month periods, only 15.5% of large-cap funds, 10.2% of mid-cap funds and 9.8% of small-cap funds were able to hold on to their top-quartile ranking. Figures were better for top-half ranking with the three above-mentioned categories holding on 32.2.%, 27.3% and 25.7%, respectively. The figures are worse over a five-year period: Only 1.9% of large caps, 3.1% and no mid-cap funds were able to maintain top quartile-rankings.