[Mutual fund attrition can create problems for a researcher because funds that disappear tend to do so due to poor performance. In this article we estimate the size of the bias by tracking all funds that existed at the end of 1976. When a fund merges we calculate the return, taking into account the merger terms. This allows a precise estimate of survivorship bias. In addition, we examine characteristics of both mutual funds that merge and their partner funds. Estimates of survivorship bias over different horizons and using different models to evaluate performance are provided.]

[We investigate the informational efficiency of mutual fund performance for the period 1965-84. Results are shown to be sensitive to the measurement of performance chosen. We find that returns on S&P stocks, returns on non-S&P stocks, and returns on bonds are significant factors in performance assessment. Once we correct for the impact of non-S&P assets on mutual fund returns, we find that mutual funds do not earn returns that justify their information acquisition costs. This is consistent with results for prior periods.]

Mutual fund attrition can create problems for a researcher because funds that disappear tend to do so due to poor performance. In this article we estimate the size of the bias by tracking all funds that existed at the end of 1976. When a fund merges we calculate the return, taking into account the merger terms. This allows a precise estimate of survivorship bias. In addition, we examine characteristics of both mutual funds that merge and their partner funds. Estimates of survivorship bias over different horizons and using different models to evaluate performance are provided.

We investigate the informational efficiency of mutual fund performance for the period 1965–84. Results are shown to be sensitive to the measurement of performance chosen. Wefind that returns on S&P stocks, returns on non-S&P stocks, and returns on bonds are significant factors in performance assessment. Once we correct for the impact of non-S&P assets on mutual fund returns, wefind that mutual funds do not earn returns that justify their information acquisition costs. This is consistent with results for prior periods.