Performance lagged behind the benchmark indices for 63.3% of large-cap funds, 80.5% of mid-cap funds and 66.5% of small cap funds.

FORBES: Best and Worst U.S. Style Indices

What is more, it is hard to know how hedge funds actually fare, since indices that track industry performance tend to overstate the returns.

ECONOMIST: The success of hedge funds

In fact, Morningstar categorizes more than 60 municipal bond mutual funds as intermediate, of which several use one of the BarCap Municipal intermediate indices or similar index as a performance benchmark.

FORBES: Put Intermediate Muni Funds In Your Portfolio's Rotation