Tracking Error

The standard deviation of the difference between an ETF's returns and its benchmark index returns. How closely the ETF follows what it's supposed to track.

Tracking Error — The standard deviation of the difference between an ETF's returns and its benchmark index returns. How closely the ETF follows what it's supposed to track.

Key facts

Category
ETF-specific
Definition
The standard deviation of the difference between an ETF's returns and its benchmark index returns. How closely the ETF follows what it's supposed to track.
Live example
/research/stock/ARKK
Last updated
2026-06-17

Interpretive bands

< 0.05%
Excellent. The largest index ETFs (VOO, IVV).
0.05 – 0.50%
Good. Most diversified index ETFs.
> 1%
Material divergence. Expected for active or thematic ETFs, problematic for passive.

How IndexAlpha uses Tracking Error

Surfaced on the ETF Performance card. A passive index ETF with high tracking error is a red flag — investigate before holding.

See it live

The Tracking Error metric shows up on every IndexAlpha research page. See it now on ARKK — or research any stock to view its Tracking Error.

Related terms

Common questions

What is Tracking Error?

The standard deviation of the difference between an ETF's returns and its benchmark index returns. How closely the ETF follows what it's supposed to track.

How does IndexAlpha use Tracking Error?

Surfaced on the ETF Performance card. A passive index ETF with high tracking error is a red flag — investigate before holding.

Sources