Do not ignore the alert. Assuming you are not in the business of buying and selling securities, when you sell the shares, you report a capital gain or loss in the year you dispose of the shares. Your alert message implies that in TurboTax you have completed a T-5008-Securities Transactions input panel and you have selected “Investment” as the “Type of Income.” If so, change it to “Capital gains” and the warning should disappear.
