Is it permissible to sell shares whose value has been paid before they are transferred to employee portfolios?

It is not permissible to sell a commodity before taking possession of it, based on the Prophet's (peace and blessings be upon him) saying: "Whoever buys food should not sell it until he has taken full possession of it." I believe everything else is similar to this. The definition of possession, in its limit, refers to custom and varies depending on what is being taken possession of. Therefore, if transferring shares to employees' portfolios is considered possession by custom, then it is not permissible to sell them before that.