Measuring Performance — TWRR, Benchmarks and What Attribution Means
Performance figures are easier to read once the method behind them is understood. This lesson explains time-weighted and money-weighted returns, how a return is compared with a benchmark, and what performance attribution does and does not show.
Two ways to measure a return
A PMS account rarely sits untouched: clients add money and take money out. That creates a measurement problem, because the value of the account changes both when the portfolio performs and when cash moves.
A time-weighted rate of return (TWRR) solves it by breaking the period into sub-periods at each cash flow, working out the portfolio's return for each sub-period, and linking those returns together. The result does not depend on when, or how much, money was added or withdrawn. It shows how the portfolio itself performed.
A money-weighted return, such as XIRR, answers a different question. It reflects the size and timing of the client's own cash flows, so it gives more weight to periods in which more money was invested. The two measures can therefore differ for the same account over the same period, and neither is wrong: one describes the portfolio, the other the client's experience of it.
Reading a return against a benchmark
A benchmark is a reference index against which the return is compared over the same period. Relative performance is the portfolio's return minus the benchmark's return.
The difference can be positive or negative, and its sign is independent of whether the portfolio made money. A portfolio that gained can still have underperformed its benchmark, and a portfolio that lost can have outperformed it. The comparison is meaningful only when both figures cover the same period.
What attribution does
Attribution is an analytical tool that splits a past difference from the benchmark into sources. The two commonly used are allocation, meaning the weights held in sectors or asset classes, and selection, meaning the securities chosen within them.
Attribution explains how a past gap arose. It does not prove skill, and it does not predict future results.
What the figures cannot do
TWRR, XIRR, relative performance and attribution all describe the past. None of them predicts how a portfolio or its benchmark will do in future, and returns are not assured.
Gaining and still lagging; losing and still ahead
The figures here are invented for arithmetic only. In one year a PMS account returns 7% after fees while its benchmark returns 11%. Relative performance is 7% − 11% = −4 percentage points: the account gained in value but underperformed its benchmark.
In another year the account returns −6% while the benchmark returns −10%. Relative performance is −6% − (−10%) = +4 percentage points: the account outperformed its benchmark, yet the client still lost money that year.
A time-weighted return with money added mid-year
- Assumptions of this example (figures invented for arithmetic only): an account starts the year at ₹1,00,00,000. Half-way through the year it is worth ₹1,10,00,000, and the client then adds ₹50,00,000, making ₹1,60,00,000. At the end of the year the account is worth ₹1,52,00,000. No other money moves.
- Return for the first sub-period: (₹1,10,00,000 − ₹1,00,00,000) ÷ ₹1,00,00,000 = 10%.
- Return for the second sub-period: (₹1,52,00,000 − ₹1,60,00,000) ÷ ₹1,60,00,000 = −5%.
- Link the two: 1.10 × 0.95 = 1.045, so the time-weighted return for the year is 4.5%.
- In rupees, the client put in ₹1,00,00,000 + ₹50,00,000 = ₹1,50,00,000 and ends with ₹1,52,00,000, a gain of ₹2,00,000 (a ₹10,00,000 gain in the first sub-period less an ₹8,00,000 loss in the second).
Result. The time-weighted return is 4.5%: that is how the portfolio itself performed. A money-weighted return on the same cash flows comes out lower, at about 1.6% for the year, because more of the client's money was invested during the weaker second half.
Key points
- TWRR measures the portfolio's own return, without the effect of when money was added or withdrawn.
- A money-weighted return, such as XIRR, reflects the size and timing of the client's cash flows.
- Relative performance is the portfolio's return minus the benchmark's return for the same period; it can be negative even when the portfolio gained.
- Attribution splits a past difference from the benchmark into sources, commonly allocation and selection.
- All of these describe the past; none predicts future results.
Common misunderstandings
- TWRR and XIRR are not interchangeable: TWRR strips out the timing of cash flows, while a money-weighted return such as XIRR reflects it.
- A positive return does not mean the benchmark was beaten: relative performance is the portfolio's return minus the benchmark's, and it can be negative when the portfolio gained.
- Attribution is not evidence of skill or a forecast: it only explains how a past difference from the benchmark arose.
- Outperforming a benchmark does not mean making money: both the portfolio and the benchmark can fall in value.
Questions people ask
Why can a client's own return differ from the return the portfolio shows?
A time-weighted return ignores when the client added or withdrew money; a money-weighted return, such as XIRR, reflects it.
What does 'underperformed by 3 percentage points' mean?
That the portfolio's return was 3 percentage points below its benchmark's for the same period, for example 9% against 12%. The portfolio may still have gained in value.
What are allocation and selection in attribution?
Allocation is the effect of the weights held in sectors or asset classes; selection is the effect of the securities chosen.
What this lesson relies on
- SEBI Master Circular for Portfolio Managers, 16 July 2025 (tagging of each investment approach to a benchmark)
- General performance-measurement definitions (time-weighted return, money-weighted return or XIRR, relative performance, attribution); no regulatory figure is relied on
This lesson was reviewed independently against these sources on 8 October 2026. Rules change: check the current regulation, scheme document or policy wording before relying on any figure. This is education, not advice.