A company's worth, or its total value, is called its market capitalization, or "market cap", and it is represented by the company's stock price multiplied by the number of shares outstanding.

For example, if Microsoft (MSFT) is trading for $71.41, on a particular day, and has 7.7 billion shares outstanding, the company is valued at $71.14 x 7.7 billion = $ 550 billion. If we take this one step further, we can see that Facebook (FB) that has a $167.40 stock price and 2.37 billion shares outstanding (market cap = $396.7 billion) is worth less than a company with a $71.41 stock price and 7.7 billion shares outstanding (market cap = $550 billion). Thus, the stock price is a relative and proportional value of a company's worth and only represents percentage changes in market cap at any given point in time. Any percentage changes in a stock price will result in an equal percentage change in a company's value. This is the reason why investors are so concerned with stock prices and any changes that may occur since a $0.10 drop in a stock can result in a $100,000 loss for shareholders with one million shares.

The next logical question is: Who sets the stock prices and how are they calculated? In simple terms, the stock price of a company is calculated when a company goes public, an event called an initial public offering (IPO). This is when a company pays an investment bank to use very complex formulas and valuation techniques to derive a company's value and to determine how many shares will be offered to the public and at what price. For example, a company whose value is estimated at $100 million may want to issue 10 million shares at $10 per share or they may want to issue 20 million at $5 a share.

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What's A Company’s Worth, And Who Determines Its Stock Price?

After a company goes public and starts trading on the exchange, its price is determined by supply and demand for its shares in the market. If there is a high demand for its shares due to favorable factors, the price would increase. If the company's future growth potential doesn't look good, sellers of the stock could drive down its price.

For more information on stocks and the factors that influence their prices, please see our article on 4 Factors That Shape Market Trends and our tutorial on Intro to Fundamental Analysis.