Market cap is the total market value of a company's outstanding shares. It represents what the market thinks a company is worth.
A company with 100 million shares at $50 each has a market cap of $5 billion.
Large-cap ($10B+): stable, blue-chip. Mid-cap ($2-10B): growth potential. Small-cap ($300M-2B): higher risk/reward. Micro-cap (below $300M): speculative.
| Category | Range | Examples |
|---|---|---|
| Mega Cap | $200B+ | Apple, Microsoft, NVIDIA |
| Large Cap | $10B - $200B | Starbucks, Delta Airlines |
| Mid Cap | $2B - $10B | Crocs, Wendy's |
| Small Cap | $300M - $2B | Emerging growth companies |
Market cap affects everything from risk profile to which funds can own the stock. Large-cap stocks are in every index fund and pension portfolio, providing stability and liquidity. Small-cap stocks can deliver outsized returns but with much more volatility.
Use market cap for portfolio allocation: A common strategy is 60-70% large cap, 20-25% mid cap, 10-15% small cap. Adjust based on your risk tolerance.
Compare market cap to revenue (P/S ratio): Market cap ÷ annual revenue reveals how much you're paying per dollar of sales. P/S of 10 is typical for high-growth tech.
Calculate Market Cap instantly:
Try PE Ratio Calculator →| Category | Range | Risk Profile | Examples |
|---|---|---|---|
| Mega Cap | $200B+ | Lower volatility | Apple, Microsoft, Saudi Aramco |
| Large Cap | $10B–$200B | Moderate | Netflix, Adobe, Nike |
| Mid Cap | $2B–$10B | Growth + stability | Crocs, Wendy's, Mattel |
| Small Cap | $300M–$2B | Higher risk/reward | Up-and-coming companies |
| Micro Cap | <$300M | Very high volatility | Startups, penny stocks |
Does a higher market cap mean a better investment?
Not necessarily. Market cap reflects size, not quality or value. A $2 trillion company can be overvalued while a $500 million company may be a bargain. Always combine market cap with valuation metrics like P/E, P/B, and EV/EBITDA to assess whether a stock is fairly priced.
Can market cap change dramatically overnight?
Yes. Market cap = share price × shares outstanding. If a stock drops 30% after earnings, the company's market cap shrinks by 30% instantly. This happens most often with small and mid-cap stocks that have lower trading liquidity.
What's the difference between market cap and enterprise value?
Market cap only counts equity value (share price × shares). Enterprise Value adds debt and subtracts cash. EV gives a fuller picture of what it would actually cost to acquire the entire company. See our Enterprise Value guide for details.