Dr. `Ali Muhyy Ed-Deen Al-Qara Daaghi, Professor of Islamic Jurisprudence at Qatar University, states the following: “If the stocks fulfil all the required conditions and were not mostly comprised of money and debts, it is permissible to buy and sell them on the same day provided that the buying and selling is registered on that same day. However, if registering did not take place on the same day, this act of buying is considered unlawful because there is no means for payment even if the payment was through what is called al-qabd al-hukmi, which is a kind of payment achieved in theory through allowing the would-be holder to act freely with it. (i.e. through selling, donating etc.)
However, in most cases, custom and nature of the property itself decides the manner of holding. Therefore, one must wait till the time of registering. However, it is permissible to buy before that as a counter measure to protect oneself from loss.”