Municipal bond mutual fund performance and active share

Abstract

This article evaluates the performance of actively managed US open-end municipal bond mutual funds between 1999 and 2020. Fund classifications span national short, intermediate, and long-term, as well as high-yield and single-state portfolios. An initial investigation reveals that municipal securities manifest characteristics of a distinct asset class. Performance measures include benchmark-adjusted returns and single- and multifactor pricing models. During the sample period, only 8% of funds generated returns that beat their benchmark indexes, and 29% produced positive excess returns (alpha) based on a four-factor pricing model. Longer-maturity funds generally performed better than short-maturity funds. Based on portfolio performance, managers specializing in single-state issues do not manifest unique knowledge or insight. Active share for the aggregate sample was 25%, implying an active expense ratio exceeding 3% and annualized active alpha below -3%. The evidence overall suggests that active management of municipal bond portfolios is not a value-enhancing activity.