📚 PASS Investment Adviser (Level 1) Difficulty: Beginner ℹ️ Info   ~5 min read
📌 Chapter 16.2 — Rate of return measures

Imagine you are reviewing a portfolio performance report for a client who invested ₹10 lakhs in an equity mutual fund on January 1st. In July, when the market was booming, the client injected an additional ₹20 lakhs into the same fund. By December 31st, the total portfolio value reached ₹35 lakhs.

If you simply calculate the internal rate of return, the heavy inflow in July masks the actual performance of the fund manager by giving more weight to the period where the capital was largest. To truly evaluate the manager’s investment prowess, you must utilize the Time-Weighted Rate of Return (TWRR).

TWRR functions by breaking the evaluation period into distinct sub-periods based on the timing of cash flows. You calculate the return for each sub-period separately—specifically, the period before the cash flow and the period after the cash flow—while assuming no external capital interference. Once these sub-period returns are isolated, you ‘chain-link’ them by multiplying (1 + r) for each period together and then subtracting one from the final product.

This mathematical operation effectively strips away the impact of the client’s decision to inject or withdraw capital, leaving only the pure performance of the underlying assets.

This methodology is essential for institutional reporting and regulatory compliance in India, particularly for Portfolio Management Services (PMS). Because the manager has no control over when a client decides to top up their investment or pull out liquidity, evaluating them based on the Money-Weighted Return would be unjust. The TWRR serves as a neutral barometer, allowing you to compare the manager’s ability to pick stocks or time sector allocations against a benchmark index.

When you present this to a client, you are telling them how the ’engine’ of the portfolio performed, independent of their own ‘fueling’ decisions.

Consider a scenario where a portfolio gains 10% in the first half of the year and loses 5% in the second half. Under TWRR, the calculation is (1.10 * 0.95) - 1, resulting in a return of 4.5%. This tells you precisely what a single unit of currency would have earned had it been invested for the full year. By ignoring the volatility of cash inflows, TWRR allows you to focus on the manager’s strategy consistency, which is the cornerstone of long-term wealth compounding and professional fiduciary duty.1

Nuance

⚠️ Nuance
A common pitfall for candidates is assuming that TWRR is always ‘better’ than MWRR. In reality, TWRR measures the performance of the portfolio, while MWRR measures the performance of the investment account including the client’s timing decisions. An analyst must be careful: if the client asks, ‘How did my money grow?’, MWRR is the correct answer. If the client asks, ‘Is my fund manager competent at stock picking?’, TWRR is the only acceptable metric.

Check Your Understanding

Practice Question 1

A portfolio starts the year with ₹100. In June, the value grows to ₹120, and the client adds ₹80, bringing the balance to ₹200. By December, the portfolio grows to ₹220. What is the approximate TWRR for the year?

Practice Question 2

Why do Indian PMS regulations prefer TWRR over MWRR for performance disclosures?

This is a companion read for Section 16.2 — Rate of return measures from PASS Investment Adviser (Level 1) by Akhilesh Gururani, available on Amazon Kindle.

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  1. TWRR is technically the geometric mean of sub-period holding period returns, effectively neutralizing the impact of external capital changes on performance metrics. ↩︎