An analysis of the dynamics of efficiency of mutual funds

This paper studies the efficiency of a sample of mutual funds that invest in the United States. Estimating a production function using Bayesian stochastic frontier analysis, we find evidence that the underlying technology presents economies of scale both at the fund and firm level. We also find evidence that informational asymmetries affect efficiency. Funds that invest domestically are likely to be more efficient than foreign funds investing in the US. Moreover, an inspection at the distribution process shows that funds sold directly to investors rather than by financial intermediaries are more efficient. The level of inefficiency persistence is overall high.Persistency of inefficiency is particularly higher for ethical funds, funds oriented to large firm sand lower in funds oriented to growth firms. The analysis done in two separate periods also shows that the efficiency of the funds changes. In particular, funds oriented to non-ethical, small and growth firms become more efficient over the period. Finally, funds' efficiency decreases during global financial crisis, but at the end of the sample period some funds recover and their efficiency levels are higher than those registered before the financial crisis. Our results have implications for investors' decisions in mutual funds.The authors acknowledge financial support from Fundação para a Ciência e Tecnologia PEst-OE/EGE/UI0315/2011 and from the Spanish Ministry of Education and Science, research project ECO2012-3240