How to Calculate Percentage Changes in Stocks

by Mark Kennan

When investors hear that a stock increased or decreased by a certain amount, it might help them to figure out how much they made or lost as a dollar amount, but it will not show the significance of the gain or loss. For example, if a stock went up by $1 and you own 100 shares, you know you gained $100, but this gain might be relatively insignificant if you invested $50,000. However, if you only invested $200, your $100 profit is much more significant. To include the investment amount in the gain or loss, represent the change as a percentage.

Subtract the initial share price of the stock from the ending share price of the stock to find the change in price. For example, if the stock started the day at $59.90 and ended the day at $59.60, subtract $59.90 from $59.60 to get a change of -30 cents, meaning you had a loss of 30 cents.

Divide the change in the stock price by the initial price per share. In this example, divide the loss of 30 cents by the initial stock price of $59.90 to get about 0.005.

Move the decimal place in 0.005 two places to the right to find the stock lost 0.5 percent of its value for the day.

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