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What Is Market Capitalisation? Large, Mid and Small Cap Explained
Market capitalisation is what the stock market values a company at. Learn the formula, how SEBI classifies large, mid and small caps, and how to use market cap.
Market capitalisation in 60 seconds
- Market capitalisation is the total value the stock market places on all of a company's shares.
- Formula: share price × total number of shares outstanding.
- In India, SEBI ranks listed companies by market cap: the top 100 are large caps, the next 150 mid caps and the rest small caps.
Educational summary — not investment advice.
Market capitalisation — market cap — is the price tag the stock market puts on a whole company. It is the simplest way to answer 'how big is this company?', and it changes every trading day with the share price.
Note that it is not the same as the company's revenue, profit or the value of its assets: it is what investors collectively think the business is worth.
How is Market capitalisation calculated?
| Measure | Formula |
|---|---|
| Market capitalisation | Current share price × Total shares outstanding |
| Free-float market cap | Share price × Shares available for public trading (excludes promoter holdings) |
Index providers such as those behind the Nifty 50 weight companies by free-float market cap, which counts only the shares actually available to trade.
Market capitalisation example with numbers
| Item | Value |
|---|---|
| Share price | ₹250 |
| Shares outstanding | 40 crore |
| Market capitalisation | ₹10,000 crore |
₹250 × 40 crore shares gives a market capitalisation of ₹10,000 crore. If the price rises 10% to ₹275, the market cap rises to ₹11,000 crore even though nothing about the company's operations has changed.
Illustrative figures. The company's business is unchanged — only the market's price for it moved.
Large cap, mid cap and small cap
SEBI classifies listed companies by their rank on average market capitalisation, and mutual funds follow these definitions.
- Large cap: the top 100 companies by market cap — established, more stable, usually lower risk.
- Mid cap: companies ranked 101 to 250 — more growth potential with more volatility.
- Small cap: company number 251 and beyond — the highest growth potential and the highest risk, with thinner trading.
Why market cap matters
- Shows a company's size relative to its sector and to the wider market.
- Helps you gauge risk: smaller companies can move sharply on small volumes.
- Is the starting point for valuation ratios such as P/E, P/B and EV/EBITDA.
- Does not include debt — two companies with the same market cap can carry very different obligations, which is why enterprise value exists.
Size, measured by the market
Market capitalisation answers a simple question: what is the whole company worth, according to the stock market, right now? It multiplies the current share price by the number of shares in issue. Because the share price changes every second during trading hours on NSE and BSE, so does market cap.
It is worth being clear about what it is not. It is not the company's sales, profit, cash or assets. It is not what someone would pay to acquire the business, which usually includes a premium and the takeover of debt. It is the price investors are collectively paying for a share of the company at this moment, scaled up to the whole.
Price is not size
One of the most common beginner mistakes is to think a stock with a high price is a big company. Share price depends on how many shares exist, which the company chooses. Compare two companies:
| Company | Price × shares = market cap |
|---|---|
| Company A | ₹4,000 × 2 crore shares = ₹8,000 crore |
| Company B | ₹40 × 300 crore shares = ₹12,000 crore |
Company B trades at one-hundredth of A's share price yet is 50% larger. Only market cap lets you compare size fairly. It also shows why a ₹40 stock is not "cheap" and a ₹4,000 stock is not "expensive": price per share alone tells you nothing about value.
Free-float market cap and index weights
Not all of a company's shares are available to trade. Promoters, governments and strategic holders often keep a large stake for the long term. The shares held by the public and institutions that can actually change hands are the free float.
Suppose a stock trades at ₹120 with 25 crore shares: market cap is ₹3,000 crore. If promoters hold 55%, the free float is 45%, so free-float market cap is ₹1,350 crore. Index providers use free-float market cap to weight companies in the Nifty 50 on NSE and the Sensex on BSE, so a company with a small free float has less influence on the index than its total market cap suggests.
Free float also affects how easily you can trade. A stock with a thin free float can move sharply on small orders and may hit circuit limits, which is one reason small caps are more volatile than large ones.
Large, mid and small caps: what really differs
| Category | What tends to be true |
|---|---|
| Large cap (top 100) | Established businesses, heavier analyst coverage, easy to trade, usually less volatile — though not immune to large falls. |
| Mid cap (101 to 250) | More room to grow, more sensitivity to the economy and to funding conditions. |
| Small cap (251 onwards) | The highest growth potential and the highest risk: thinner trading, less information and bigger swings. |
AMFI publishes the list twice a year, so a company can move between categories as its market cap rises or falls relative to others. Benchmarks such as the Nifty 100, Nifty Midcap 150 and Nifty Smallcap 250 from NSE Indices track each group.
Market cap and valuation: from equity value to enterprise value
Market cap is the starting point for valuation ratios. P/E is market cap divided by profit; price-to-sales is market cap divided by revenue; price-to-book is market cap divided by equity. But market cap ignores debt and cash. Two companies with the same market cap and the same profit can be very different investments if one carries heavy debt.
Enterprise value fixes this by adding debt and subtracting cash: EV = market cap + debt − cash. When you compare companies with different financing, EV-based ratios such as EV/EBITDA are fairer than those based on market cap alone.
Mistakes to avoid
- Believing a low share price means a cheap stock.
- Assuming a large market cap means safety. Big companies can fall a long way.
- Ignoring free float when judging how easily a stock can be bought or sold.
- Forgetting that market cap changes with new share issues, buybacks, splits and bonuses.
- Using market cap alone to compare valuations without looking at debt.
Test yourself
- Question 1. Price ₹120, 25 crore shares. Market cap? Answer: ₹3,000 crore.
- Question 2. Promoters hold 55%. Free-float market cap? Answer: 45% of 3,000 = ₹1,350 crore.
- Question 3. The price rises 20%. New market cap? Answer: ₹3,600 crore.
- Question 4. A company splits each share into two. What happens to market cap, all else equal? Answer: nothing; the price halves and the share count doubles.
Next, see how market cap feeds into EV/EBITDA and how P/E and price-to-book turn it into a valuation.
On NSE and BSE: what to keep in mind
- On NSE and BSE, market cap is quoted in ₹ crore. The Nifty 50 (NSE) and Sensex (BSE) are weighted by free-float market cap.
- AMFI publishes SEBI's large, mid and small cap list twice a year, and mutual funds follow it.
- Nifty 100, Nifty Midcap 150 and Nifty Smallcap 250 from NSE Indices are commonly used benchmarks for large, mid and small caps.
Market capitalisation: frequently asked questions
Is a bigger market cap always better?
No. A large cap is usually more stable but may grow more slowly; a small cap can grow faster but carries more risk.
Does market cap tell me if a stock is cheap?
No. A company's market cap says how big it is, not whether it is fairly priced. For that, use valuation ratios such as P/E and P/B.
How often do the large, mid and small cap lists change?
SEBI's list is revised by AMFI every six months, based on average market cap, so companies can move between categories.
Disclaimer: this article is for education only. The figures in the worked example are illustrative and do not describe any real company listed on NSE or BSE. It is not investment advice, and investingg.in is not a SEBI-registered advisor.
The bottom line
Market cap is the market's price for the whole company. It tells you size and helps frame risk, but it says nothing about whether the price is a bargain.
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Disclaimer: This analysis is for educational purposes only and should not be considered investment or trading advice. Please consult your financial advisor before making investment decisions.