We empirically analyze the nature of returns to scale in active mutual fund management. We find strong evidence of decreasing returns at the industry level: As the size of the active mutual fund industry increases, a fund's ability to outperform passive benchmarks declines. At the fund level,...

We model optimal fund turnover in the presence of time-varying profit opportunities. Our model predicts a positive relation between an active fund's turnover and its subsequent benchmark-adjusted return. We find such a relation for equity mutual funds. This time-series relation between turnover...