Note that the trust will be required to file an income tax return (Form 1041) if it has gross income of $600 or more for the tax year or any taxable income for the tax year.
See https://www.irs.gov/instructions/i1041#en_US_2021_publink1000285943
Also, note that the trustee, depending upon the terms of the trust, can distribute the stocks, in kind, to the beneficiary(ies) and avoid filing a return entirely (assuming there is no other income or gain).
