3 Ways Not All ETFs are the Same

The ETF's rebalancing method can be another source of mis-tracking. As the components and weightings of an index change over time, the fund must buy and sell holdings in an attempt to match it. Let's say a fund's optimised technique results in a slight underweighting in a handful of stocks that are in the index and that just happen to have better performance. In that case, the fund's total return may not match that of the index, and the fund will now be even more underweight in those stocks, causing tracking difference. In a sense, the ETF's expense ratio itself creates a form of tracking difference because fees are deducted from returns.

How can you tell if mis-tracking is at play with your ETF? One way is to check the tracking error of the ETF, i.e. how volatile the fund’s excess returns are relative to the index. If the tracking error is high--say, 40 basis points or more--inefficient management may be to blame. However, tracking error isn't necessarily a bad thing. In fact, ETFs with high tracking error may outperform those with low tracking error. Also, some indices are simply more difficult to track than others.

Another way to assess the tracking quality of your ETF is to check its annual tracking differences. The gap between the fund’s annual returns versus the index’s should be close to the fund's expense ratio. If tracking difference is considerably wider, further research may be needed to understand why.

Subtle Index Differences
Another issue to keep in mind when comparing ETFs within the same category is that they may not track the same index. For example, some Chinese equity ETFs track the CSI 300 Index; however, another ETF might track the MSCI China A Index. Given its larger number of constituents (445 vs. 300), the MSCI China A Index is slightly more diversified, with more mid-cap exposure. And as a result, the ETFs that track the MSCI China A will behave slightly differently from those that track the CSI 300 Index, depending on the market environment.

These differences can get even more complex when dealing with ETFs that track indices with value or growth tilts. That's because even though blended benchmarks typically include or exclude companies based on their market caps, indices that focus exclusively on value or growth stocks typically apply their own proprietary screens based on variables such as company fundamentals and stock price. A company that qualifies for one value-oriented index may not qualify for another. Consequently, value- or growth-oriented ETFs may have portfolios that vary from one another to a greater extent than one might find among ETFs tracking a blended benchmark, especially one that includes highly liquid stocks.

ETFs tend to be rather straightforward, easy-to-own, and cost-effective investment vehicles. By educating yourself about how they differ from one another, you can help make sure they perform as expected.