Zakat on Investments in a Minor Child's Name

Short answer: Yes — per the majority (Malik, ash-Shafiʿi, Ahmad; also the fatwa of Ibn Baz and al-Uthaymin), zakat is due on the wealth of minors and the insane, because zakat is a right attached to the wealth itself — legal responsibility of the owner is not a condition. The guardian pays it from the child's own wealth and keeps account. Details: Umar (ra) said: 'Trade with the orphans' wealth lest sadaqah consume it,' and Aisha (ra) paid zakat on the wealth of orphans under her care — the Companions knew minors' wealth owes zakat. The usual conditions apply to the child's own estate (where the gift was genuine): his wealth must itself reach nisab and complete a hawl, reckoned separately from the father's. Money merely parked in the child's name while really yours remains your wealth — zakated in your books. Evidence: Quran 9:103 (general); Sahih al-Bukhari 1395 (taken from 'their rich' — a wealthy minor is rich); the well-known athar of Umar (Muwatta) and the practice of Aisha. For complex individual cases, consult a qualified scholar.