<prompt> Human: Question edit: bought 100 shares of stock at 1 each 100 total worth, stock rose to 10 each 1000 total worth, sold 10 shares for 100, what do I owe for short term capital gains tax?Would I owe a percentage on that 100? or would that count as my initial investment and not be taxed?Thanks for the help. EDIT: Im an idiot and cant math.  <response>: You bought 1 share at 1. You sold this one share at 100. You made a profit of 99. Your capital gain is 99.1. It doesnt matter what the stock rose to. Only how much you boughtsold matters.2. Think in units of shares. 