If you didn't sell the stock or deem it "worthless security" within the same year as your gain, you can't use that loss against your gain. You need to have proof of the loss. If you made 30k on a stock and didn't do anything with the other one you have to pay the taxes on the 30k.
Register for free to join our community of investors and share your ideas. You will also get access to streaming quotes, interactive charts, trades, portfolio, live options flow and more tools.