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NISM Series XXI-B Short Notes – Part 10: Performance Measurement, GIPS & Portfolio Rebalancing

12 Apr 2026 • NISM-Series-21B: Portfolio Managers Mock Tests

 

NISM Series XXI-B Short Notes – Part 10: Performance Measurement, GIPS & Portfolio Rebalancing

This is the final part (Part 10) of our 10-part NISM XXI-B short notes series on PassNISM.in. This part covers Chapters 20 and 21 — Performance Measurement & Evaluation of Portfolio Managers and Portfolio Rebalancing. These chapters are heavily tested in the NISM Series XXI-B exam, particularly the risk-adjusted return ratios.

👉 Also Read: Part 9: Equity & Fixed Income Portfolio Strategies | Free Mock Test

Chapter 20: Performance Measurement & Evaluation of Portfolio Managers Why Performance Measurement Matters

There is a natural human tendency to focus only on returns — ignoring the risk taken to achieve them. Proper performance measurement must evaluate both return and risk together. A portfolio with high returns achieved by taking excessive risk is not necessarily a good portfolio.

Rate of Return Measures

Measure Description
Holding Period Return (HPR) Total return over the investment period: (End Value – Begin Value + Income) / Begin Value
Time-Weighted Rate of Return (TWRR) Eliminates the impact of external cash flows (client deposits/withdrawals). Standard method for comparing portfolio managers. Reflects the manager's skill independently of client cash flows.
Money-Weighted Rate of Return (MWRR) IRR of the investment; affected by timing and size of cash flows. Reflects the actual investor experience (including the impact of their own cash flow decisions).
Arithmetic Mean Return Simple average of period returns. Best for single-period analysis.
Geometric Mean Return Compound growth rate; more appropriate for multi-period performance measurement.
CAGR (Compounded Annual Growth Rate) The steady rate at which an investment would have grown to its final value over the holding period.
Gross vs Net Return Gross = before fees; Net = after fees. Net return is what the investor actually earns.
Pre-Tax vs Post-Tax Return Post-tax return reflects the actual return after accounting for tax obligations.
Cash Drag Adjusted Return Adjusts for idle cash held in the portfolio that doesn't generate full market returns.
Alpha and Beta Return Beta return = market return component; Alpha return = excess return from active management skill.

📌 TWRR is the SEBI/GIPS preferred measure for comparing portfolio managers — because it removes the distortion caused by client-driven cash flows.

Risk Measures Total Risk

Standard Deviation (σ): Measures dispersion of portfolio returns around the average. A higher standard deviation means higher total risk (more volatile returns). Portfolio standard deviation is not the weighted average of individual standard deviations — it also depends on the correlations between assets.

Downside Risk

Semi-Variance / Semi-Standard Deviation: Measures only the downside — dispersion of returns below the mean (or below a target return). This is preferred by investors who view risk as "losing money" rather than "volatility in general." For symmetrically distributed returns, semi-variance is proportional to variance.

Systematic Risk

Beta (β): Measures the sensitivity of a portfolio's returns to the benchmark/market index returns. It is the measure of systematic (non-diversifiable) risk.

Tracking Error

Tracking Error: Standard deviation of the difference between portfolio returns and benchmark returns. It measures how closely the portfolio follows its benchmark. Lower tracking error = more consistent benchmark tracking.

Risk-Adjusted Return Ratios (Most Important for Exam) 1. Sharpe Ratio

Sharpe Ratio = (Rp – Rf) / σp

Where: Rp = Portfolio return, Rf = Risk-free rate, σp = Portfolio standard deviation

The Sharpe ratio measures excess return per unit of total risk. It is a relative performance measure — higher Sharpe ratio means better risk-adjusted performance. It allows comparison of portfolios with different risk levels. Uses total risk (standard deviation) in the denominator.

2. Treynor Ratio

Treynor Ratio = (Rp – Rf) / βp

Where: βp = Portfolio beta

The Treynor ratio adjusts excess return for systematic risk (beta). It measures return per unit of market risk. A fund with a higher Treynor ratio in relation to another is preferable — it has earned more return per unit of market risk taken. Uses beta (systematic risk) in the denominator.

3. Sortino Ratio

Sortino Ratio = (Rp – Rf) / Semi-Standard Deviation of Portfolio

The Sortino ratio adjusts excess return for downside risk only. It is particularly useful for investors who care about avoiding negative outcomes rather than managing total volatility. Replaces standard deviation with semi-standard deviation in the denominator.

4. Information Ratio

Information Ratio = Active Return / Tracking Error
= (Rp – Rb) / Tracking Error

Where: Rb = Benchmark return

The Information Ratio measures a manager's ability to generate excess returns relative to the benchmark per unit of active risk (tracking error). A higher Information Ratio indicates greater skill in active management.

5. M² Measure (Modigliani-Modigliani Measure)

The M² measure adjusts a portfolio's return to match the risk level of the market portfolio, making comparison more intuitive. It scales the portfolio risk to equal the market's risk, then compares returns.

Summary: Comparing the Four Key Ratios

Ratio Risk Measure Used Best Used For
Sharpe Total risk (σ) Comparing diversified portfolios
Treynor Systematic risk (β) Comparing funds with different betas
Sortino Downside risk (semi-σ) Investors focused on avoiding losses
Information Ratio Active risk (tracking error) Evaluating active manager's skill

Performance Attribution Analysis

Attribution analysis dissects portfolio return into two main components:

  • Benchmark return – What the market/index delivered
  • Differential return (Active return / Alpha) – What the manager added beyond the benchmark

Sources of Differential Return

  1. Asset/Sector Allocation: Differential return from overweighting sectors that outperformed or underweighting sectors that underperformed the benchmark.
  2. Security Selection: Differential return from choosing individual securities that outperformed or avoiding those that underperformed the benchmark.

Due Diligence in Portfolio Manager Selection

Selecting a portfolio manager involves far more than just reviewing past returns. Thorough due diligence includes:

  • Reputation and track record analysis
  • Evaluation of key personnel and their experience
  • Assessment of operational infrastructure
  • Understanding of investment process, strategy, and style
  • Gauging the likelihood that the past performance approach will persist

Global Investment Performance Standards (GIPS®)

GIPS provides the investment community with ethical standards for presenting investment performance results. They serve to:

  • Provide greater uniformity and comparability among investment managers globally
  • Facilitate transparent dialogue between managers and prospective clients about performance and strategy
  • Ensure fair representation and full disclosure in all performance presentations

GIPS applies to both existing and prospective clients, and to investment managers worldwide — regardless of geographic location.

Chapter 21: Portfolio Rebalancing Why Rebalancing Is Necessary

Portfolio management doesn't end with construction. After building the portfolio, it must be continuously monitored and periodically rebalanced. Two primary reasons for rebalancing:

  1. Market Condition Changes: Asset prices change at different rates, causing the portfolio to drift from its target Strategic Asset Allocation (SAA).
  2. Investor Circumstance Changes: The investor's goals, risk tolerance, or life stage may change, requiring a new SAA.

Costs and Benefits of Rebalancing

There is an inherent trade-off in rebalancing:

  • Cost: Transaction costs, taxes triggered by selling, and the time/effort of executing the rebalance.
  • Benefit: Maintaining the intended risk-return profile; avoiding unintended risk concentration; staying aligned with investor objectives.

Rebalancing reduces the present value of expected loss from deviating from the optimal strategic allocation.

Periodicity of Rebalancing Time-Based (Calendar) Rebalancing

The portfolio is rebalanced after a fixed time period — monthly, quarterly, half-yearly, or annually. Simple to implement and understand, but may lead to unnecessary transactions if markets haven't moved significantly.

Threshold-Based (Trigger) Rebalancing

Rebalancing occurs only when asset class weights drift beyond a pre-specified tolerance band (e.g., ±5% from target weight). More efficient in terms of transaction costs but requires constant monitoring.

Three Rebalancing Strategies 1. Buy and Hold Strategy

A passive approach — the initial strategic asset allocation is set and then left unchanged. No rebalancing occurs. Over time, the winning asset classes grow to dominate the portfolio, causing significant drift from the original allocation and a higher-risk profile than originally intended.

2. Constant Mix Strategy

A dynamic "do-something" strategy. The portfolio is periodically traded to maintain the original asset mix. When an asset class falls in value, more is purchased; when it rises, some is sold to bring weights back to target. Benefits:

  • Maintains consistent risk exposure (unlike buy and hold, which lets risk drift up)
  • Naturally implements a "buy low, sell high" discipline

Constant Mix tends to outperform Buy and Hold in volatile, mean-reverting markets.

3. Constant Proportion Portfolio Insurance (CPPI)

CPPI is an active rebalancing strategy that dynamically allocates between:

  • Risky assets (e.g., equities) — for growth potential
  • Risk-free assets (e.g., government bonds) — for downside protection

CPPI aims to provide the upside potential of risky assets while protecting against catastrophic downside loss below a defined floor value.

Key CPPI concept:

Investment in Risky Asset = Multiplier × (Portfolio Value – Floor Value)

Where Floor Value = minimum acceptable portfolio value (downside protection level)

As the portfolio grows above the floor, more is invested in risky assets. As the portfolio approaches the floor, funds are moved into safer assets.

Comparing the Three Strategies

Strategy Approach Risk Management Best in
Buy and Hold Passive; no trading after initial setup Risk drifts upward over time Trending (bull) markets
Constant Mix Rebalance back to original target weights Maintains consistent risk profile Volatile, oscillating markets
CPPI Dynamic allocation between risky and safe Protects downside with defined floor Trending markets with downside protection needs

Final Quick Revision Box – Part 10 (Complete Series Summary) Key Formulas Summary

  • CAPM: E(Ri) = Rf + β × (Rm – Rf)
  • Sharpe Ratio: (Rp – Rf) / σp
  • Treynor Ratio: (Rp – Rf) / βp
  • Sortino Ratio: (Rp – Rf) / Semi-σp
  • Information Ratio: (Rp – Rb) / Tracking Error
  • CPPI: Risky Allocation = Multiplier × (Portfolio Value – Floor)

Last-Minute Exam Points

  • TWRR = preferred for manager evaluation (not affected by client cash flows)
  • Sharpe uses total risk; Treynor uses beta; Sortino uses downside risk; IR uses tracking error
  • GIPS = global ethical standard for presenting investment performance
  • Constant Mix = "buy low, sell high" discipline; good in volatile markets
  • CPPI = dynamic strategy with floor protection
  • Buy and Hold = let drift happen; riskier over time
  • Attribution: return = benchmark return + allocation effect + selection effect

🎯 Complete NISM XXI-B Short Notes Series Index

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