Market Capitalization Explained
5 min read · Updated June 30, 2026
Market capitalization — "market cap" — is the simplest measure of how big a company is in the eyes of the stock market. It is one of the first numbers investors check.
It also clears up a common beginner confusion: a high share price does not make a company large, and a low one does not make it small.
How market cap is calculated
Market cap equals the share price multiplied by the number of shares outstanding. A company with 10 billion shares trading at $50 has a market cap of $500 billion.
Because it accounts for the total number of shares, market cap reflects the whole company’s value — not just the price of a single share.
Large, mid, and small cap
Companies are loosely grouped by size. Large-cap companies are typically worth roughly $10 billion or more, mid-caps fall in between, and small-caps are usually under about $2 billion.
Large-caps tend to be more established and less volatile; smaller companies can grow faster but often carry more risk. The S&P 500 is made up almost entirely of large-caps.
Why market cap matters more than price
A $500 share price tells you nothing about a company’s size on its own — it depends on how many shares exist. A company at $500 with few shares can be worth far less than one at $20 with billions of shares.
This is why investors compare companies by market cap, not share price, and why a stock split (which changes the price but not the market cap) does not change what a company is worth.
Frequently asked questions
How is market cap calculated?
Market capitalization is the current share price multiplied by the total number of shares outstanding. For example, 1 billion shares at $100 each gives a $100 billion market cap.
What is a large-cap stock?
A large-cap stock is generally a company with a market capitalization of about $10 billion or more. These tend to be well-established companies, and they make up most of the S&P 500.
Does a higher share price mean a bigger company?
No. Share price alone does not indicate size because it depends on how many shares exist. Market capitalization — price times shares outstanding — is the correct measure of a company’s size.