How to Calculate Market Price Change of Common Stock

by Bryan Keythman ; Updated April 19, 2017
A stock's market price changes as investors trade shares.

Shares of a company’s common stock represent an ownership interest in the company. The shares can trade on a stock exchange, or over the counter through a network of dealers. A company’s common stock price is the price investors are willing to pay for a single share of stock. The market price fluctuates as investors buy and sell shares. You can calculate the change in the market price of a common stock to measure an investment’s performance.

Step 1

Visit any financial website that provides stock information.

Step 2

Type a company’s name or ticker symbol in the text box required to search for the company’s stock information. A ticker symbol consists of letters that are an abbreviation of the company’s name or something related to the company’s business. Then click the button next to the text box to bring up the company’s current stock price. For example, assume a company’s current stock price is $14.

Step 3

Click on the historical prices section of the company’s stock quote information. Find the company’s stock price on a previous date, such as the date on which you purchased the stock. In this example, assume the company’s stock price was $10 one year ago.

Step 4

Subtract the previous stock price from the current stock price to calculate the change in price. A positive result means the stock’s price increased. A negative number means the stock has decreased in price. In this example, subtract $10 from $14 to get $4. This means the stock’s price increased by $4.

Step 5

Divide the change in stock price by the previous price. Then multiply the result by 100 to calculate the percentage change in stock price. Continuing with the example from the previous steps, divide $4 by $10 to get 0.4. Multiply 0.4 by 100 to find a 40 percent increase in the stock’s price.

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