NISM Series XXI-B Short Notes – Part 6: Indices, Market Efficiency & Behavioural Finance
This is Part 6 of our 10-part NISM XXI-B short notes series on PassNISM.in. This part covers Chapters 12, 13, and 14 — Stock Market Indices, the Concept of Informational Efficiency, and Behavioural Finance. These are conceptual and high-scoring chapters in the NISM Series XXI-B exam.
👉 Also Read: Part 5: Taxation & Regulatory Aspects | Free Mock Test
Chapter 12: Introduction to Indices What is a Market Index?
A stock market index is an indicator that reflects the performance of a selected group of securities, acting as a proxy for the broader market. The idea is that performance of individual investments tends to be linked to the overall performance of the market they belong to.
The world's first security market index was introduced by Charles H. Dow and Edward D. Jones in 1884 — the Dow Jones Average.
Uses of Market Indices
- Providing a gauge of the market's overall performance
- Benchmarking investment portfolios and active fund managers
- Serving as the underlying portfolio for index funds and ETFs
- Acting as a proxy for the market portfolio of risky assets
Key Factors Differentiating Indices
- Sample size (number of stocks included)
- Weighting methodology used for each constituent
Index Weighting Methodologies
| Method | How It Works | Example |
|---|---|---|
| Price Weighted | Weights assigned based on stock price. Sum of constituent prices ÷ divisor. | Dow Jones Industrial Average |
| Value Weighted (Market Cap Weighted) | Weights based on market capitalization (price × shares outstanding). Most common globally. | NIFTY 50, S&P 500 |
| Free Float Weighted | Uses only shares available for public trading (excludes promoter, government holdings). | Most modern indices |
| Equal Weighted | Every constituent gets the same weight, regardless of price or market cap. | Some factor-based indices |
| Fundamental Weighted | Weights based on fundamental factors like book value, dividends, cash flows, sales. | RAFI indices (Alternative/Smart Beta) |
📌 Criticism of Market Cap Weighting: It overweights overvalued stocks and underweights undervalued stocks. Fundamental weighting was developed to address this flaw.
Free Float
Free float represents the actual availability of a company's shares for public trading. It excludes strategic (control) holdings like promoter stakes and government holdings, since those are not driven by economic value considerations but by control motives.
Types of Stock Market Indices
- Broad-Based Indices: Represent an entire market segment (e.g., NIFTY 500, BSE 500).
- Market Cap Based Indices: Large Cap, Mid Cap, Small Cap indices tracking different size segments.
- Style Indices: Value indices (undervalued stocks) and Growth indices (high-growth stocks).
- Capitalization + Style Indices: Combinations like Large Cap Value, Mid Cap Growth, etc. — useful for benchmarking specific portfolio styles.
- Sectoral Indices: Track performance of specific industries (banking, IT, pharma, auto, etc.).
Total Return Index (TRI)
Most indices are price indices — they only capture capital gains (price changes), ignoring dividend income. A Total Return Index includes both capital gains AND dividends received, giving a truer picture of actual investment returns. Regulatory bodies now mandate comparison against TRI for active funds.
Other Index Types
- Dollar Denominated Index: Measures returns on Indian equity in US dollar terms — useful for foreign investors assessing returns in their home currency.
- Global Equity Indices: Cover multiple countries; allow comparison of developed vs emerging markets (e.g., MSCI World Index).
Bond Market Indices
- Government Securities Index: Tracks performance of Indian sovereign securities (G-Secs).
- Corporate Bond Index: Measures performance of corporate bonds across different duration buckets and rating segments (e.g., NIFTY AAA, AA+ Bond Indices).
- High Yield Bond Index: Tracks bonds rated below investment grade (below BBB).
- Global Bond Index: Covers government, government-sponsored, and corporate bonds from 100+ countries, including 18,000+ unique bonds.
- Total Return Bond Index: Includes price movements + accrued interest + cash flows from bonds.
Composite (Stock-Bond) Indices
Composite indices blend equities and bonds, making them useful for evaluating portfolios with exposure to both asset classes. These include Hybrid Indices.
Chapter 13: Concept of Informational Efficiency Operational Efficiency vs Informational Efficiency
- Operational Efficiency: Measures the cost of transacting in the market — lower transaction costs = more operationally efficient market.
- Informational Efficiency: A market is informationally efficient when prices are unbiased estimates of securities' true value. Deviations of price from value are random in nature (not systematic).
The Efficient Market Hypothesis (EMH)
EMH states that in an efficient market, security prices fully and instantly reflect all available information. The early treatment of efficient markets was based on the Random Walk Hypothesis — the idea that price changes occur randomly, with no predictable pattern.
Three Forms of Market Efficiency
| Form | Information Reflected in Price | What this Means for Analysis |
|---|---|---|
| Weak Form | All historical price and volume data | Technical analysis based on past prices does NOT yield excess returns |
| Semi-Strong Form | All historical + all publicly available information | Fundamental analysis of public information does NOT yield excess returns |
| Strong Form | All historical + public + private (insider) information | Even insider information cannot earn excess returns |
📌 Each form includes all the information of the form below it. Strong form encompasses semi-strong form, which encompasses weak form.
Market Anomalies (Violations of EMH)
- January Effect: Stock returns tend to be higher in January (especially small caps).
- Size Anomaly: Smaller companies tend to outperform larger companies after adjusting for risk.
- Value Anomaly: Value stocks (low PE, low PB) tend to outperform growth stocks over long periods.
EMH and Technical Analysis
In a weak-form efficient market, analyzing past price data cannot help predict future price movements — because all such historical information is already reflected in current prices. Technical analysis adds no value in a weak-form efficient market.
EMH and Fundamental Analysis
In a semi-strong form efficient market, public information is already priced in. Fundamental analysis based on publicly available data cannot generate superior risk-adjusted returns.
The Internal Contradiction in Market Efficiency
Markets don't become efficient on their own. It is the very act of analysts and traders seeking to exploit mispricings that makes markets efficient. Therefore, the necessary condition for markets to be efficient is that enough participants believe markets are inefficient and act on that belief. This is the fundamental paradox of the efficient market concept.
Rise of Index Funds and EMH
Globally, passively managed index fund AUM has grown significantly. The logic: in an efficient market, it is hard to consistently beat the market after accounting for transaction costs. A strategy of minimizing transaction costs through indexing outperforms frequent active trading, especially for long-term investors.
Chapter 14: Behavioural Finance What is Behavioural Finance?
Behavioural Finance studies how psychology influences market participants — both at individual and group levels — and the resulting impact on financial markets. It is part of Behavioural Economics, which identifies cognitive biases and emotional errors that affect investment decisions.
Assumptions of Standard Finance vs Reality
Standard finance assumes investors are:
- Fully rational
- Risk-averse
- Self-interested utility maximizers
- Updating beliefs as new information arrives
- Having access to all available information
Behavioural finance challenges these assumptions and shows that real investors deviate significantly from this ideal.
Bounded Rationality
When time is limited or information is incomplete, decision-making favors a satisficing solution (one that is satisfactory and sufficient) rather than the mathematically optimal one. This is called bounded rationality — it is not irrational, but rational decision-making within real-world constraints.
Prospect Theory
Prospect Theory describes how people evaluate potential gains and losses in risky decisions. It shows that:
- People feel losses more strongly than equivalent gains (loss aversion)
- How a decision is framed affects the choice made
- People overweight small probabilities and underweight high probabilities
Emotional Biases
| Bias | Description |
|---|---|
| Loss Aversion Bias | Pain of losing is felt more intensely than pleasure of equivalent gains. Leads to holding losers too long and selling winners too early. |
| Stereotype / Representativeness Bias | Judging situations by how closely they resemble stereotypes rather than statistical probability. |
| Overconfidence Bias | Overestimating one's own skill and ability in predicting outcomes; excessive trading. |
| Endowment Bias | Valuing something more highly simply because you own it. |
| Status Quo Bias | Preference for the current state of affairs; resistance to change. |
Cognitive Errors
| Error | Description |
|---|---|
| Mental Accounting | Treating money differently based on its source or intended use (e.g., treating a bonus as "different" from regular salary). |
| Framing | The same information presented differently leads to different decisions. |
| Anchoring Bias | Over-relying on the first piece of information encountered when making decisions (e.g., anchoring to a stock's purchase price). |
Fusion Investing
Fusion Investing integrates traditional (fundamental) analysis with behavioural insights. It acknowledges that while intrinsic value exists (as fundamental analysis suggests), short-term prices are heavily influenced by collective investor behavior and emotions — leading to mispricings that behaviorally-aware investors can exploit.
Behavioural Finance and Market Bubbles/Crashes
Behavioural finance helps explain why bubbles form and eventually burst. Contributing factors include:
- Liquidity: Excessive liquidity fuels speculative buying
- Celebrity Status: Herd behavior around trending assets or personalities
- Momentum: Trend-following amplifies price moves beyond fundamentals
- Illusion of Control: Investors overestimate their ability to manage or predict outcomes
Quick Revision Box – Part 6
- First stock market index: Dow Jones Average (1884)
- Free float = shares available for public trading (excludes promoter stakes)
- TRI = price return + dividends (truer measure of return)
- Weak EMH → no value in technical analysis
- Semi-strong EMH → no value in fundamental analysis
- January Effect, Size Anomaly, Value Anomaly = market anomalies contradicting EMH
- Prospect Theory = people feel losses more than equivalent gains
- Loss aversion, overconfidence, anchoring = key biases for exam
👉 Continue Reading: Part 7: Modern Portfolio Theory & Capital Market Theory
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