Since your child's income is less than $2,100, are not required to report the income on your tax return. However, that is an option available to you. The better option is not to include the gain on your tax return, but to treat the income as your child's. Since your child's unearned income is less than $1,050, the child is not required to file a tax return. In other words, the gain will go untaxed.
Please follow this link for more information. https://www.irs.gov/publications/p929/ar02.html#en_US_2016_publink1000203791
