What it means
Active risk is calculated as the standard deviation of active returns, meaning the variability of the gap between portfolio and benchmark performance. It does not measure whether the manager is winning or losing, only how far and how often the portfolio strays from the yardstick.
This is important because it puts outperformance in context. A manager who beat the index by 1% while barely deviating from it has done something quite different from a manager who beat it by 1% while swinging wildly above and below all year.
Institutional investors typically set an active risk budget when they hire a manager, for example a mandate that must stay within 3% tracking error. The manager is then free to pick stocks inside that boundary but cannot quietly turn a core holding into a concentrated speculative fund.
The figure is normally computed from monthly active returns over three to five years and then scaled to an annual number. Some houses use ex-post active risk, based on what actually happened, while risk teams often prefer ex-ante active risk, which a model estimates from the current holdings before the results are known.
The most common use of active risk is as the bottom half of the information ratio, where active return is divided by active risk. That ratio tells you how much reward the manager generated for each unit of deviation they took, which is a fairer scorecard than raw outperformance alone.
In practice
Real-world examples.
Example
A local government pension scheme hires two equity managers with identical 2% average outperformance. One shows active risk of 1.5% and the other 5.0%, so the scheme allocates more money to the first because it delivers the same reward with far less deviation.
Example
A fund platform screens its catalogue and finds a supposedly active fund running active risk of just 0.4%. The team flags it as a closet tracker, since investors are paying active fees for something that behaves almost exactly like the index.
Example
A risk officer at an asset manager notices active risk on a balanced mandate has climbed from 2.1% to 4.3% over two quarters. Investigation shows the portfolio manager has doubled a technology position, breaching the 3% risk budget agreed with the client.
Formula
Calculation
Active Risk = standard deviation of (Portfolio Return - Benchmark Return) across periods
A fund reports five years of active return: +3%, -1%, +2%, 0% and +1%.
Step 1, find the average active return: (3 - 1 + 2 + 0 + 1) / 5 = 5 / 5 = 1%.
Step 2, find each deviation from that average: +2, -2, +1, -1 and 0.
Step 3, square each deviation and add them: 4 + 4 + 1 + 1 + 0 = 10.
Step 4, divide by the number of periods minus one: 10 / 4 = 2.5.
Step 5, take the square root: the square root of 2.5 is 1.58, so active risk is 1.58%.
The information ratio is then average active return divided by active risk: 1% / 1.58% = 0.63. A ratio above 0.5 is generally considered respectable for a long-only equity manager.Case study
Seen in the real world.
The Kestrel Lane Pension Scheme is a fictional, illustrative retirement fund used here to show how active risk changes a hiring decision. Its trustees shortlisted two equity managers who had both averaged 1% of active return a year over five years.
The scheme's adviser calculated active risk for each. The first manager's yearly active returns were +3%, -1%, +2%, 0% and +1%, giving active risk of 1.58% and an information ratio of 0.63. The second manager had reached the same 1% average through a run of large swings, producing active risk of 4.9% and an information ratio of only 0.20.
The trustees appointed the first manager and wrote a 2.5% active risk limit into the mandate, with quarterly monitoring. They accepted that this would cap the upside in a spectacular year, judging that a predictable relationship with the benchmark mattered more to a scheme paying pensions every month.
Watch out
Common mistakes.
- Reading a high active risk figure as bad management, when it simply describes deviation from the benchmark and says nothing about whether that deviation was profitable.
- Confusing active risk with total portfolio volatility, which measures the ups and downs of the portfolio itself rather than the gap between portfolio and index.
- Calculating active risk from only a handful of monthly observations, which produces an unstable number that swings around with each new data point.
Questions
People also ask.
Is active risk the same as tracking error?
Yes, the two terms are used interchangeably in almost all investment reporting.
What is a normal level of active risk?
Index trackers usually sit below 0.5%, mainstream active funds around 2% to 5%, and concentrated or specialist strategies can exceed 8%.
Does zero active risk mean zero risk?
No, it only means the portfolio moves in step with its benchmark, and if that benchmark falls 30% the portfolio will fall with it.
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