Tracking Error measures how consistently an index fund or ETF stays close to its benchmark — higher tracking error means more divergence from the target index.
Tracking error is the standard deviation of the difference between a fund's returns and its benchmark's returns over a period. For passive funds (index funds, ETFs), lower tracking error is better — the fund is closely replicating its target index. For active funds, tracking error is used in the Information Ratio calculation. A high tracking error in a passive fund may indicate poor replication, high transaction costs, or cash drag.
If a Nifty 50 index fund is supposed to exactly match the Nifty 50 index, tracking error measures how much it strays. A fund that perfectly tracks the index has near-zero tracking error. A fund that sometimes gains or loses 1–2% more/less than the Nifty has higher tracking error — meaning you're not getting pure index exposure.
Calculate daily/monthly difference: fund return − benchmark return.
Calculate standard deviation of these differences over a period (typically 1 year).
Lower is better for passive funds (target is exact replication).
For active funds, low tracking error with positive information ratio = value added consistently.
Causes of high tracking error in index funds: cash drag, expense ratio, dividend reinvestment timing, corporate actions.