The "tracking-error" shows the difference between an asset's actual return vs. its benchmark's return. The tracking-error is presented as a standard deviation during 52 weeks. In cases of less than 52 weeks, it is calculated on an annualized bi-weekly basis as soon as a minimum of 13 weeks are available.

The lower the tracking-error number, the closer the asset is performing to its benchmark. Monthly measures are more stable and reliable than bi-weekly measures.

Formula: standard deviation of (asset's monthly return - benchmark index's monthly return)