Every evening the news reports that "the market" went up or down by some number of points. That number is an index, and understanding how it is built tells you why it so often disagrees with what happened to your own portfolio.
What an index is
An index is a single number summarising a basket of stocks. The NIFTY 50 tracks 50 large NSE-listed companies; the SENSEX tracks 30 on the BSE. Crucially, both are weighted by free-float market capitalisation — bigger companies move the number more.
The indices worth knowing
| Index | What it tracks | Why you would watch it |
|---|---|---|
| NIFTY 50 | 50 largest, most liquid NSE stocks | The default benchmark for Indian equity |
| SENSEX | 30 established BSE companies | The longest continuous record — data back to 1979 |
| BANKNIFTY | 12 large banks | The most heavily traded derivative in India; banks drive the index |
| NIFTY Next 50 | The 50 after the top 50 | Where tomorrow’s largecaps come from |
| NIFTY Midcap 150 | Ranks 101–250 by market cap | Higher growth, much higher drawdowns |
| India VIX | Expected 30-day volatility | The "fear gauge" — spikes when the market panics |
Largecap, midcap, smallcap
These are not vague adjectives in India — SEBI defines them precisely by rank, and mutual funds are legally bound by the definitions.
| Category | SEBI definition | Character |
|---|---|---|
| Largecap | Ranks 1–100 by full market cap | Established, well covered by analysts, liquid, slower growth. Falls least in a crash. |
| Midcap | Ranks 101–250 | Proven businesses still scaling. Meaningfully more volatile. |
| Smallcap | Rank 251 onwards | Everything else — from genuine future compounders to shells. Thin liquidity, wide spreads, brutal drawdowns. |
Why you cannot beat the index by accident
An index fund buys the whole basket for a fee of a few basis points and never panics. Beating it requires being right about something the rest of the market has not yet worked out — repeatedly, after costs and taxes. That is possible, and some people do it. But it should be a deliberate decision made with open eyes, not the unexamined default.
On a given day 34 of the NIFTY 50 stocks closed lower, yet the NIFTY closed up 0.6%. How?
Poore desh mein hazaaron cricketer hain, par "India kaisa khel raha hai" jaanna ho toh aap playing XI dekhte ho. NIFTY 50 wahi playing XI hai — 2,000 companies mein se top 50. Largecap matlab senior khiladi, midcap under-19 se aaya talent, smallcap gully cricket ka star — kabhi dhamaal, kabhi ekdum flop.
- Indices are weighted averages — the biggest companies dominate the number.
- A rising index with falling breadth is a narrow, fragile rally.
- SEBI defines largecap as ranks 1–100, midcap 101–250, smallcap 251 onwards.
- Smallcap upside and smallcap drawdowns are the same coin. Size positions accordingly.
- India VIX spikes signal genuine fear, not routine weakness.
Mark it done to track your progress through the curriculum.
Common questions
Short, direct answers to what people ask about this topic.
- how many companies are in the NIFTY 50
- The NIFTY 50 tracks 50 of the largest, most liquid companies listed on the NSE, weighted by free-float market capitalisation. It is one of India’s two headline indices and is meant to represent the broad large-cap market, so its level is used as shorthand for how “the market” did on a given day.
- difference between NIFTY and SENSEX
- Both are Indian benchmark indices, but the SENSEX tracks 30 companies on the BSE while the NIFTY 50 tracks 50 companies on the NSE. They move very closely together because they hold many of the same large firms; the main differences are the exchange, the number of constituents and the base value each is calculated from.
- how does SEBI define largecap midcap and smallcap
- SEBI defines the buckets by rank of full market capitalisation: the top 100 listed companies are large-cap, the next 150 (ranks 101–250) are mid-cap, and everything from rank 251 onwards is small-cap. The list is revised periodically, and mutual funds must classify their schemes against these definitions.
- why can the NIFTY rise on a day most stocks fall
- Because the NIFTY is weighted by free-float market cap, a handful of the largest companies dominate its movement — if those heavyweight stocks rise, the index can climb even when the majority of smaller stocks fall. The index measures the value-weighted market, not the count of winners versus losers.
- what does India VIX measure
- India VIX is a measure of the market’s expectation of volatility over the near term, derived from NIFTY options prices — often called the “fear gauge”. A rising VIX signals traders expect larger swings ahead, while a low VIX suggests calm; it indicates expected volatility, not the direction the market will move.