WSJ added another featured story to the neve-eding comparison of ETFand index-tracking mutual fund performance. The result? Based on Morninstar's calclation, mutual funds stay ahead in most of the games.

We asked research firm Morningstar Inc. to crunch performance data back to 1997 for some of the biggest and best-known ETFs and index funds in each of four categories: the Standard & Poor's 500-stock index, the total U.S. stock market, international stock markets and a broad-based U.S. bond index.

These are the core areas for small investors trying to build a diversified portfolio. We also examined after-tax performance data that fund companies are required to disclose.

The conclusion: Big, low-cost index funds from Boston-based Fidelity Investments and Vanguard Group Inc., Malvern, Pa., outperformed the ETFs in most of the comparisons we set up. For the 40 time periods studied, the mutual funds prevailed in 34 -- including a sweep of the one-, three-, and 10-year after-tax categories.

To their credit, ETFs sold by Barclays and State Street almost always beat the average performance of index mutual funds in their respective categories. But so did the big, low-cost index funds. Average returns for each category were calculated by looking at all of the index funds in Morningstar's database, not just those considered in this contest.