Press F1 when you are on that box and you will get

1 If Securities Trader Transaction

Select the box (or enter 1) if the transaction is from a trading business rather than an investment activity. If an entry is made in this field, the program prints “(Trader Transaction)” after the description of the asset. However, an entry in this code does not trigger the program to report the transaction on Form 4797, Part II for a trader to which the mark-to-market method of accounting applies due to an election under IRC section 475(f). To report a security transaction on Form 4797, Part II, enter “-1” in “Depreciation allowed (-1 if none, triggers 4797)” (code 30). If the security was held for more than a year, also enter “2” in “1=short-term, 2=long-term [O]” (code 51).

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