Is it permissible to trade gold and currencies in global and electronic markets, now that their prices have become volatile?

The fundamental condition for the permissibility of selling gold for silver or currencies, or selling different currencies to each other, is the occurrence of taqabud (mutual possession) in the contract session. The evidence for this is the saying of the Prophet, peace and blessings be upon him: "If it is hand to hand, then there is no harm; but if it is deferred, then it is not permissible." And nasi'a (deferred) means delay. And his saying, peace and blessings be upon him: "We were commanded to buy silver with gold as we wished, and to buy gold with silver as we wished." He said, then a man asked him: "Hand to hand?" He replied: "This is what I heard." Possession occurs by each contracting party delivering what is due to the other, hand to hand or into their bank account. If they are geographically separated, then possession occurs by each authorizing someone to act on their behalf in the delivery. If the condition of taqabud is violated, the two contracting parties fall into riba an-nasi'a (usury of delay).