In a previous article, we highlighted a flaw in the average credit quality statistic frequently reported by bond mutual funds. That statistic understates the credit risk in bond portfolios if the portfolios contain bonds of disperse credit ratings. In this article we address a similar problem with bond mutual funds' reporting of the average term of their portfolios. The somewhat ambiguous nature of this statistic provides an opportunity for portfolio managers to significantly increase the funds' risks, credit risk in particular, by holding very long-term bonds while claiming to expose investors to only the risks of very short-term bonds.
Morningstar uses a fund-provided statistic - the average effective duration - to classify funds as ultra short, short, intermediate or long-term. Funds have figured out how to hold long-term bond portfolios yet be classified as ultra short-term and short-term bond funds. We show that extraordinary losses suffered by these funds in 2008 can be explained by the how much the bond funds' unadulterated weighted average maturity exceeded the maturities typically expected in short-term bond funds.