ETFs, Index Funds and Tracking Error in Plain English
Funds that follow the same benchmark can still produce different investor outcomes after costs and portfolio implementation.
An exchange-traded fund holds investments under stated rules and trades on a market, while an index fund describes an investment strategy that seeks to track a benchmark. An ETF can be index-based or actively managed. Likewise, a traditional mutual fund can track an index. The terms should not be treated as interchangeable product categories.
Tracking error measures variation between a fund's returns and a chosen benchmark over a period; a persistent fee drag can also cause tracking difference. Cash holdings, sampling, taxes, securities lending and trading costs all influence implementation. The benchmark may be price return or total return, which changes the comparison.
Before evaluating a fund, read its prospectus, expenses, investment policy, trading spread and the exact benchmark version. Buying an index-linked product is not equivalent to buying an index itself. The SEC's investor education materials explain why fund risks and costs still matter.
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