> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chicago.global/llms.txt
> Use this file to discover all available pages before exploring further.

# Market Capitalization

> Understanding market capitalization - how company size is measured and why it matters

Market capitalization (market cap) is the total market value of a company's outstanding shares. It's the primary measure of company size in investing and forms the basis of major stock indices.

## Beginner

### What It Means

Market cap tells you what the market thinks a company is worth. It's calculated by multiplying the stock price by the total number of shares outstanding.

```
Market Cap = Share Price × Shares Outstanding
```

### Example

| Company   | Share Price | Shares Outstanding | Market Cap    |
| --------- | ----------- | ------------------ | ------------- |
| Company A | \$50        | 2 million          | \$100 million |
| Company B | \$200       | 500,000            | \$100 million |

Both companies have the same market cap despite very different share prices. Share price alone doesn't tell you company size.

### Size Categories

| Category      | Market Cap Range        | Examples                    |
| ------------- | ----------------------- | --------------------------- |
| **Mega-Cap**  | >\$200 billion          | Apple, Microsoft, Amazon    |
| **Large-Cap** | \$10B - \$200B          | Most S\&P 500 companies     |
| **Mid-Cap**   | \$2B - \$10B            | Regional leaders            |
| **Small-Cap** | \$300M - \$2B           | Growing companies           |
| **Micro-Cap** | Less than \$300 million | Very small public companies |

### Why It Matters

Market cap determines:

* Which indices include a stock (S\&P 500, Russell 2000, etc.)
* How much of an index a stock represents
* Liquidity and trading characteristics
* Risk and return expectations

***

## Advanced

### Market Cap vs. Other Size Measures

| Measure              | Definition               | Use Case                                  |
| -------------------- | ------------------------ | ----------------------------------------- |
| **Market Cap**       | Price × Shares           | Most common size measure                  |
| **Enterprise Value** | Market Cap + Debt - Cash | Acquisition value, better for comparisons |
| **Revenue**          | Annual sales             | Size of operations                        |
| **Total Assets**     | Balance sheet assets     | For financials, regulated industries      |

### Float-Adjusted Market Cap

Most indices use float-adjusted market cap:

```
Float-Adjusted Market Cap = Price × Float Shares

Float Shares = Total Shares - Insider Holdings - Restricted Shares
```

This counts only shares actually available for trading, excluding:

* Insider holdings (executives, founders)
* Government holdings
* Strategic holdings by other companies
* Restricted stock

### Index Weighting

Market cap determines portfolio weights in cap-weighted indices:

```
S&P 500 Example (simplified):
- Apple: $3T market cap → ~7% of index
- Small company: $50B market cap → ~0.1% of index
```

<Note>
  Cap-weighted indices are "self-rebalancing" - as stocks rise, their weight naturally increases. No trading required to maintain weights.
</Note>

### The Size Factor

Academic research documents the "size premium" - historically, smaller companies have outperformed larger ones:

| Period    | Small-Cap Premium     |
| --------- | --------------------- |
| 1926-2023 | \~2-3% annually       |
| 1980-2000 | Significant           |
| 2000-2020 | Near zero or negative |

<Warning>
  The size premium has been inconsistent in recent decades. Small-cap outperformance is not guaranteed and comes with higher volatility.
</Warning>

### Market Cap Characteristics by Size

| Characteristic         | Large-Cap | Small-Cap |
| ---------------------- | --------- | --------- |
| Volatility             | Lower     | Higher    |
| Liquidity              | High      | Lower     |
| Analyst Coverage       | Extensive | Limited   |
| Information Efficiency | High      | Lower     |
| Trading Costs          | Low       | Higher    |

### Dynamic Nature

Market cap changes continuously:

* Stock price movements
* Share buybacks (reduces shares, may increase price)
* Stock issuance (increases shares, may decrease price)
* Stock splits (no effect on market cap)

### Sector Distribution by Size

Different sectors dominate different size segments:

| Segment   | Dominant Sectors                    |
| --------- | ----------------------------------- |
| Mega-Cap  | Technology, Healthcare              |
| Large-Cap | Financials, Industrials             |
| Mid-Cap   | Industrials, Consumer               |
| Small-Cap | Financials, Healthcare, Industrials |

### Limitations

* **Price-Based**: Reflects market sentiment, not intrinsic value
* **Volatile**: Can change dramatically with price swings
* **Debt-Blind**: Doesn't account for leverage (use Enterprise Value)
* **Industry Differences**: Hard to compare across sectors

### Related Terms

<CardGroup cols={3}>
  <Card title="Beta" href="/glossary/beta">
    Small caps typically have higher beta
  </Card>

  <Card title="Factor Investing" href="/glossary/factor-investing">
    Size is a key factor
  </Card>

  <Card title="Diversification" href="/glossary/diversification">
    Across size segments
  </Card>
</CardGroup>