There are no statutory provision prohibiting a someone under the age of 18 (a minor) from owning shares in an ADGM entity.
However, a contract to purchase shares is unlikely to be enforceable against a minor because it is not considered a necessity. This will make it difficult to enforce payment for the shares against a minor. For this reason, some companies will amend their Articles of Association to specify that they do not accept shareholders under the age of 18 or take this approach informally.
In many family owned companies, shares are allotted to children as a means of providing them with capital assets which may be expected to increase in value as part of longer term inheritance and capital gains tax planning. In many such cases, different classes of shares are set up so that the child may, for example, have non-voting shares, or so that the directors can pay different rates of dividends on the various classes, giving flexibility as to how the company's profits are distributed. Such schemes should only be set up with professional tax and legal advice.