Is the banking transaction permissible by Sharia in which the bank directly purchases shares in the client's name and places them in the client's portfolio, while taking a pledge from the client not to dispose of them until the Murabaha contract is completed and the restriction is lifted, and then the bank sells them to the client, knowing that the bank takes a power of attorney to dispose of the shares if the client defaults? And does the bank, by doing so, truly own and possess the shares, or is it a deception? And is it permissible for the bank to purchase shares in its own name and portfolio and then authorize the client to sell them?