Get the original cost base of the stock, which includes the market price and brokerage commissions. If you cannot find this information in your records, ask your broker or look for it on websites that show historical price information. For example, if you bought 100 shares at $10 per share in January 2010 and paid $22 in commission charges, the cost base per share is $10 plus 22 cents ($22 divided by 100), or $10.22 per share.
Factor in the effect of stock splits or reverse stock splits. A stock split increases the number of shares and reduces the price per share, while a reverse split decreases the number of shares and increases the price per share. For example, a two-for-one stock split halves the price per share and doubles the share count, while a 10-for-one reverse stock split reduces the number of shares by a factor of 10 and increases the stock price tenfold.
Obtain the current price of the stock. Sources for this information include your online broker, the company's investor relations page and other websites that display real-time or historical stock quotes.
Subtract the purchase price from the current price to calculate the stock price appreciation. Divide the price appreciation by the cost and multiply the result by 100 to express the price appreciation as a percentage. Continuing with the example, if the current stock price is $14 per share, the price appreciation is $14 minus $10.22, or $3.78 per share. In percentage terms, the price appreciation is 100 multiplied by ($3.78 divided by $10.22), or about 37 percent, which is the return on the initial investment. If you sell the stock, the profit will be slightly lower because of broker commissions.
Compute the total stock return from price appreciation and dividend payments. Some companies pay cash dividends to their shareholders from after-tax income. Add the dividends to the stock price appreciation to compute the total return. In the example, if the company has paid $2 in dividends since your purchase, the total stock return is $3.78 plus $2, or $5.78 per share. In percentage terms, the total stock return is 100 multiplied by ($5.78 divided by $10.22), or approximately 56 percent. This calculation assumes that you have not added to or subtracted from the stock position. In other words, the cost base has not changed from the original purchase.
Compare the stock appreciation with other stocks in the market. Yahoo! Finance, MSN Money and other websites provide research tools for comparing stocks based on price appreciation and other factors.