The effect of portfolio weighting on investment performance evaluation: The case of actively managed mutual funds

Among the factors influencing investment performance measurement is the weight dedicated to each security. This paper develops metrics for measuring the extent of equal weighting and value weighting of a portfolio. A sample of 506 actively managed mutual funds shows that funds tend to be equally weighted to a greater degree than they are value weighted, implying that investment performance based solely on a single value-weighted benchmark may not adequately identify excess performance. We propose a two-factor model utilizing both a value-weighted and an equally weighted index and show that the model provides a better fit than the single-index model.