Yes, as it is unearned income over $1,050. IRS does not look at cost basis and if no return is filed they may send a notice with $0 basis and short term gain.
Dependents who have unearned income, such as interest, dividends or capital gains, will generally have to file their own tax return if that income is more than $1,050 for 2018 (income levels are higher for dependents 65 or older or blind).
