How to Calculate Market Price Change of Common Stock

Common stock prices fluctuate on a daily and even hourly basis. But as an investor, what matters most isn't the current price of the stock so much as the change in stock price. Obviously, you want your stocks to increase in value during the period that you hold them. Calculate the price change for common stock to see if your investments are turning a profit or a loss.

Write down the beginning stock price. For example, assume that you want to calculate the change in price of the stock since you purchased it, and the purchase price was $11.50 per share. In this case you would write down $11.50 as your beginning stock price.

Write down the end stock price. For example if you were calculating the price change up to the present, you would write down the stock's current price. Assume for the sake of example that the current price of the stock is $13. Write that figure down.

Subtract the beginning price from the end price to get the change in price as a dollar value. A positive number indicates an increase in price, while a negative number indicates that the price has decreased. For example, if you subtract a beginning price of $11.50 from the end price of $13, you have a price increase of $1.50.

Calculate the change as a percentage by dividing the dollar value of the change by the starting price and multiplying the result by 100. For example, if you have a change of $1.50 and a starting price of $11.50, then you would have an increase of 13 percent.