lawful purposes and activities is permissible.
(b) There is unanimous agreement that it is forbidden to buy shares in a company whose principal purpose is unlawful—such as dealing in interest, producing prohibited items, or trading in them.
(c) The basic ruling is that it is impermissible to participate in companies that occasionally engage in prohibited dealings, like interest-based transactions and the like, even though their core activities are lawful.

2 – ḍamān al-iṣdār (underwriting)
Underwriting is an agreement, at the time a company is founded, with a party that undertakes to guarantee all or part of the share issue by pledging to subscribe to whatever portion others leave unsubscribed. This is permissible in the Sharīʿah provided the underwriter commits to purchase at the nominal value and receives no compensation for the guarantee itself. The underwriter may, however, be paid for services other than the guarantee—such as preparing feasibility studies or marketing the shares.

3 – Paying for shares in instalments at subscription
There is no legal objection to paying part of the share’s price at the time of subscription and deferring the remaining instalments. Such an arrangement constitutes participation with the capital already advanced and a mutual promise to increase the capital later, and it entails no harm, since it applies to all shares. The company remains liable to outsiders for its full declared capital, which is the amount known to and accepted by those who deal with it.

4 – Bearer shares
Because what is sold in a “bearer share” is an undivided interest in the company’s assets, and because the share certificate merely evidences that entitlement, it is permissible under the Sharīʿah for a company to issue and trade in shares of this type.