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how to calculate the rate of return on selling a stock?
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you probably want the internal rate of return (irr), see http://en.wikipedia.org/wiki/internal_rate_of_return which is the compound interest rate that would produce your return. you can compute it in a spreadsheet with xirr(), i made an example: https://spreadsheets.google.com/ccc?key=0avutw2htdqfydesxvlm0rfdrrk1qs1honurxzkvfn3c&hl=en you can also use a financial calculator, or there are probably lots of web-based calculators such as the ones people have mentioned.
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