What it is
Market capitalization is the share price multiplied by the number of shares. A company with 1 billion shares at $50 has a market cap of $50 billion. It is what the stock market says the whole company's equity is worth today.
Size categories
| Category | Market cap |
|---|---|
| Mega cap | Above $200 billion |
| Large cap | $10 billion to $200 billion |
| Mid cap | $2 billion to $10 billion |
| Small cap | $300 million to $2 billion |
| Micro cap | Below $300 million |
Cut-offs vary between index providers. Larger companies tend to be steadier; smaller ones have more room to grow and more ways to fail.
Market cap versus enterprise value
Market cap ignores debt and cash. Enterprise value adds debt and subtracts cash, giving the price of the whole business. See EV/EBITDA.
Market cap versus potential
A useful research question: how big could this company become? Compare its market cap with the size of its market and the value of the leaders in similar markets.
- A $25 billion company in a market where peers reached $200 to $500 billion has room to grow.
- A $10 billion company in a $100 billion market could grow several times if it wins share.
- A company already worth most of its entire market has to grow the market itself.
This is a sanity check, not a formula. See How to research a company.
See also
- EV/EBITDA EV/EBITDA values a whole company, debt included, against its operating cash earnings. How enterprise value works and when to use it over P/E.
- How to research a company A step-by-step way to research a stock: understand the business, run a SWOT, apply the double-or-halve test, then check the numbers and valuation.
- Index funds What index funds are, why low-cost index investing beats most professional fund managers over time, and how to use index funds as a portfolio core.
Last updated September 30, 2026. Education only, not investment advice.