Nobody should blindly ignore his finances, and investment portfolios are no exception. Even if you subscribe to the "buy, hold and ignore" mentality, it's a good idea to periodically track your portfolio's performance. Knowing if your investment is gaining or losing value assists financial planning and identifies potential investment shortcomings. Although dollar value gains or losses are helpful to tabulate your total return, converting those figures to percentages captures your return with respect to your original investment, and that more usefully describes performance regardless of the investment amount.
Calculate your stock portfolio's initial value. This might be as simple as looking for the figure on your investment account's statement. If you don't have that figure, multiply the number of shares by the initial cost per share, and then add the totals of each stock. For example, if you bought 50 shares of stock XYZ for $50 and 100 shares of stock ABC for $20, your total initial value is $4,500 (calculated as 50 times $50, plus 100 times $20). If you can't find the purchase price or number of shares, contact your investment broker for this information.
Look up the current value of each stock on any financial website, such as MSN Money, Yahoo! Finance or Google Finance.
Multiply the number of shares of each stock by the current values, and then add the totals to calculate your current portfolio value. Continuing with the prior example, if stock XYZ rose to $60 per share, but stock ABC dropped to $10 per share, your current total value is $4,000 (calculated as 50 times $60, plus 100 times $10).
Subtract the current value from the original value to calculate the change in value. Extending the example, $4,500 minus $4,000 equals -$500, which signifies a loss of $500.
Divide the change in value by the original investment, and then multiply by 100 to convert to a percentage: -$500 divided by $4,500 equals -0.111. Multiplying by 100 converts this figure to -11.1 percent, meaning your portfolio experienced an 11.1 percent loss in value.
When calculating actual returns from stock sales, you must subtract any fees charged from the change in value. If the example transactions cost $50 for the initial purchase and for the subsequent sale, the change in value is -$600, resulting in a 13.3 percent loss.
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