Market Cap and Why It Is Important

3 Types of Market Cap

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Market capitalization is the total market value of a company. It's measured by the stock price multiplied by the number of shares issued. For example, a company that has one million shares that are selling for $10 each would have a market capitalization of $10 million. This means you could buy that company for $10 million if you had the money and all the current stockholders were willing to sell you their shares.

Market capitalization is usually called "market cap" for short. It also refers to the total value of a stock exchange. For example, the market cap of the Nasdaq would equal the market cap of all the companies traded on the Nasdaq combined.

Key Takeaways

  • Market capitalization is a company's total value in the stock market.
  • The value of a company is calculated by the number of shares a company has times the price the stocks are selling at. 
  • Companies are separated into three different groups by investors depending on their market cap: small, medium, and large.
  • Small-caps have greater room for growth, medium caps have room for growth and stability, while large-cap companies have the most amount of stability.

Small, Medium, and Large-Cap

Investors typically use market cap to divide the stock market into three broad size categories.

Small-cap companies have market capitalizations between $300 million to $2 billion. They are smaller companies, many of which recently went through their initial public offerings. They are riskier because they are more likely to default during a downturn. On the other hand, they have lots of room to grow and could become very profitable. The smallest small-caps, with market caps of $250 to $300 million, are called "micro caps," where as those with market caps less than $50 million are often referred to as nanocaps.

Mid-cap companies have capitalizations of between $2 billion and $10 billion. Such companies are typically in the growth phase of their business cycle, working toward expanding market share and increasing competitiveness. They can offer more growth potential than large-cap companies and can carry less risk than small-cap companies.

Large-cap companies have the least risk, because they typically have the financial resources to weather a downturn. Since they tend to be market leaders, they may have less room to grow. The return might not be as high as small- or mid-cap stocks. On the other hand, they are more likely to reward stockholders with dividends. The market cap for these companies is $10 billion or more.

Market Cap Is a Good Way to Value Companies

Market cap is a relatively good way to quickly value a company. That's because stock prices are generally based on investors' expectations of a company's earnings. As earnings rise, stock traders will bid more for the stock price. Including the number of shares in the calculation offsets the impact of stock splits.

Market cap would be a great way to value companies if they all had the same price to earnings ratio. Investors consider some industries to be slow growing or stodgy. Their stock prices are undervalued, and so are the market caps of companies in that industry.

There are several other ways to determine the value of a company. One good way is to determine the net present value of its future cash flow or income. This gives the buyer an idea of what the return on investment will be. If a company's market cap is lower than the net present value of its cash flow, then it is undervalued, and a candidate for takeover.

Another more conservative approach is to determine the total resale price of a company's assets. The drawback is that some assets would be difficult to value. Others may be worth more than their resale value. However, this is a good approach for a company that just wants to buy another company and sell off the assets for quick cash.


A company with a market cap much lower than its resale value would be a target for this kind of takeover.

During the Internet bull market in 1999, many companies' capitalization values were worth far more than their income or asset value. Irrational exuberance drove stock prices beyond a reasonable valuation. When the tech bubble burst, it led to the recession of 2001. 

2021 Largest Companies by Market Cap

In 2018, Apple became the first company traded in the U.S. to cross $1 trillion in market capitalization and just two years later it was the first to surpass the $2 trillion market cap milestone as well.

Here's a list of the top 20 largest companies traded in the U.S. by market cap as of April 2022:

  1. Apple: $2.8 trillion
  2. Microsoft: $2.4 trillion
  3. Alphabet (Google) Class C: $1.8 trillion
  4. Amazon: $1.6 trillion
  5. Tesla: $1.1 trillion
  6. Berkshire Hathaway A: $763 billion
  7. NVIDIA: $615 billion
  8. Meta (formerly Facebook): $609 billion
  9. United Health Group: $497
  10. Johnson & Johnson: $475 billion
  11. Visa: $462 billion
  12. Walmart: $423 billion
  13. JP Morgan Chase: $388 billion
  14. Procter & Gamble: $375 billion
  15. Exxon Mobil: $355 billion
  16. Mastercard: $346 billion
  17. Chevron: $321 billion
  18. Bank of America: $320 billion
  19. Home Depot: $311 billion
  20. Alibaba: $309 billion

Most of these companies are all well-known, household names. Many have been on the top 20 list for years.

Frequently Asked Questions (FAQs)

How do crypto market caps work?

Cryptocurrencies use coins instead of shares, but the market capitalization concept remains the same. You can calculate a coin's market cap by multiplying all circulating coins by the price of each one. Crypto typically exhibits greater price volatility than stocks, so a coin's market cap will also fluctuate rapidly.

Why is market cap important?

Unlike individual share prices, the market cap quickly gives investors a sense of the total size of a company. The stocks with the biggest market caps become known as "blue chip" stocks, and these stocks offer relatively stable histories of growth and dividend payments. The market cap also gives you insight into how a stock trades. The larger the market cap, the more likely the stock will be liquid with a reasonable bid-ask spread.

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The Balance uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Financial Industry Regulatory Authority. "Market Cap, Explained."

  3. University of Pennsylvania, The Wharton School. “Crossing $1 Trillion: What’s Next for Apple?

  4. S&P Global Market Intelligence. “Apple Market Cap Now About 1.5x Entire US Banking Industry.”

  5. TradingView. “U.S. Stock Market.” Click on each ticker to view marketcap.

  6. Securities and Exchange Commission. "Investor Alert: Bitcoin and Other Virtual Currency-Related Investments."

  7. Office of Investor Education and Advocacy. "Stocks."

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