Mutual Fund Survivorship

This paper offers a comprehensive study of survivorship issues, in the context of mutual fund research, using the mutual fund data set of Carhart (1997). We find that funds in our sample disappear primarily because of multi-year poor performance. Then we demonstrate analytically that this survival rule typically causes the survivor bias in average performance to increase in the length of the sample period, though it is possible to construct counterexamples. In the data, we find a strong positive relation between the survivor bias in average performance and sample period length. The bias is economically small at 17 basis points per annum for one-year samples, but a significantly larger one percent per annum for samples longer than fifteen years. We also find evidence of performance persistence in our sample and, consistent with the presence of a multi-period survival rule, we find that the persistence is weakened by survivorship bias. Finally, we explain how the relation between performance and fund characteristics can be affected by the use of a survivor-only sample and show that the magnitudes of the biases in the slope coefficients are large for fund size, expenses, turnover and load fees in our sample. Because survivorship issues are relevant for many data sets used in finance, the analysis in this paper has potential applications in areas of financial economics beyond just mutual fund research.