Large, Mid & Small Caps

Market capitalization sorts companies by size, from giants worth trillions to small firms worth a few hundred million. Here is how the size groups are defined and how they have behaved over two decades.

Market cap in one line

Market capitalization is the total value of a company’s shares: share price times shares outstanding. A company with 1 billion shares at $50 has a market cap of $50 billion. It measures the company’s size in the stock market, not its sales or profits.

Market cap: a few giant companies make up a large share of the market’s total value.

Unlock all of Investing School

The rest of this lesson, its chart examples and quiz are part of Investing School. Start free with Stock Market Fundamentals and the first lesson in every category.