These two scenarios can create an environment where performance expectations of investors may not be met due to the tracking error versus the underlying commodity index that is created.

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In order to achieve zero tracking error, the fund manager must hold exactly the index for every second of the day.

FORBES: Getting Over Index Investing With A Better Way

The expectation that an index fund will get EXACTLY the return of the target index sets the stage for an interesting problem: Zero tracking error is achievable, but it comes at a very high price.

FORBES: Getting Over Index Investing With A Better Way