I recently received an email from a reader, J.W., who wanted to know why the tracking error on some popular Vanguard international equity ETFs were so high in 2014. He noted, for example, that the Vanguard FTSE Developed ex North America (VDU) lagged its benchmark index by 1.62% last year, far more than one would expect.
An index fund’s tracking error is the difference between the performance of the fund itself and that of its benchmark. If the index returns 10% on the year and the fund delivers 9.8%, the tracking error is 0.20%, or 20 basis points. But what could possibly cause a fund to show a tracking error of 162 basis points?
Any time you see a surprising number like this, it’s important to determine the reason: otherwise you risk making a bad decision because you’re working with inaccurate or misleading information. If an index were to lag its benchmark by more than 1.6% because it was badly managed, then you should look for a better alternative. But Vanguard has a long record of tight tracking error, so something else has to be going on here—and indeed it is.
Back on track
To understand VDU’s large tracking error—and why it’s not as bad as it looks—let’s look at the reasons its performance deviated so far from the index.