A comparable return in a taxable security would be 7.75 percent for investors in a 28 percent tax bracket and 8.33 percent in a 33 percent bracket.

The comparable return in a taxable security for investors in a 28 percent tax bracket is 7.89 percent, and 8.48 percent in a 33 percent bracket.

To earn a comparable return in taxable securities, the equivalent yield to investors in a 28 percent tax bracket would have to be 8.30 percent.

A comparable return in taxable securities would be 8.01 percent for investors in a 28 percent tax bracket, and 8.61 percent in a 33 percent bracket.

For those in a 33 percent bracket, the comparable return would have been 8.45 percent.

The limits have often been set above comparable returns in other industries.

They put together a diversified index of commodities and found that it provided a return and volatility comparable to that of the S.&P. 500.

For most shareholders, this means the tax-adjusted return is about three percentage points higher than a comparable return on another fund, Mr. Levine said.

For most investors, this structure creates tax-adjusted returns that are about three percentage points higher than comparable returns on other funds, he said.

The comparable return for the Standard & Poor's 500-stock index was 13.8 percent.