How to Calculate Stock Market Capitalization and Why It Is Important

What's that company worth?

Stock Market Capitalization
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A company's stock market capitalization is an important concept that every investor should understand. Although market capitalization is often discussed on the nightly news and used in financial textbooks, you may not know how stock market capitalization is calculated. You may also be confused as to how it differs from or how it differs from the figures that arise in discussions of mergers and acquisitions. In the next few moments, I'm going to help change that.

The Definition of Stock Market Capitalization

Put simply, stock market capitalization is the amount of money it would cost if you were to buy every single share of stock a company had issued at the then-current market price. 

How to Calculate Stock Market Capitalization

The formula for calculating stock market capitalization is as simple as it sounds. There are no tricks or weird quirks to consider. It's this straightforward:

Stock Market Capitalization = Current Shares Outstanding x Current Stock Market Price

Real-World Examples of How to Calculate Stock Market Capitalization

As of July 31, 2018, The Coca-Cola Company [NYSE: KO] has 4,252,922,000 shares of stock outstanding and the stock traded at $46 per share. If you wanted to buy every single share of Coca-Cola stock in the world, it would cost you 4,252,922,000 shares x $46 = $195,634,412,000. That is more than $195 billion. On Wall Street, people would have referred to Coca-Cola's market capitalization as $195 billion.  

The Strengths and Weaknesses of Stock Market Capitalization

Stock market capitalization can allow investors to understand the relative size of one company versus another, ignoring specifics about capital structure that cause the share price of one firm to be higher than another firm. For example, compare Coca-Cola at $46 per share with retailer Netflix at $341 per share. Despite having an exponentially larger share price, the latter has a stock market capitalization of $161 billion, more than $30 billion smaller than Coke's. To learn more about this topic, check out my article How to Think About Share Price, which walks you through the math, explaining how a $300 stock might be cheaper than a $10 stock.

On the flip side, stock market capitalization is limited in what it can tell you. The biggest downfall of this particular metric is that it does not factor into consideration a company’s debt. Consider Coca-Cola once more. The company has around $27 billion in liabilities that, were you to buy the entire business, you would be responsible for servicing and repaying. That means, while Coke's stock market capitalization is $195 billion, it's enterprise value is $222 billion because, simplified and all else equal, the latter figure is what you would need to not only buy all of the common stock but pay off all the debt, too. To learn more about this topic, read my article Enterprise Value – Determining the Takeover Value of a Company.

Another major weakness of using stock market capitalization as a proxy for a company's performance is that it does not factor in distributions such as spin-offs, split-offs, or dividends, which are extremely important in calculating a concept known as total return. It seems strange to many new investors, but total return can result in an investor making money even if the company itself goes bankrupt. For one historical example, look at the long-term performance of the collapse of Eastman Kodak. Aside from dividends collected over the years, the owners ended up with shares of a chemical company, so the fact market capitalization went to zero didn't mean they necessarily lost everything.


Using Market Capitalization to Build a Portfolio

Many professional investors divide their portfolio by market capitalization size. These investors do this because they believe that it allows them to take advantage of the fact smaller companies have historically grown faster but larger companies have more stability and pay fatter dividends.

Here is a breakdown of the type of market capitalization categories you are likely to see referenced when you begin investing. The exact definitions tend to be a bit fuzzy around the edges, but this is a pretty good guideline.

  • Micro Cap: The term micro cap refers to a company with a stock market capitalization of less than $250 million.
  • Small Cap: The term small cap refers to a company with a stock market capitalization of $250 million to $2 billion.
  • Mid Cap: The term mid cap refers to a company with a stock market capitalization of $2 billion to $10 billion.
  • Large Cap: The term large cap refers to a company with a stock market capitalization of $10 billion to $100 billion.
  • Mega Cap: The term mega cap refers to a company with a stock market capitalization of more than $100 billion.

Again, be sure to check the specifics when using these definitions. For example, a person might refer to a company with a stock market capitalization of $5 billion as being large cap under certain circumstances.

More Information About Stock Investing

For more information on stocks, read our Complete Guide to Investing in Stock.