It is perfectly possible that they directly exchange stocks but denominate prices (and wages, contracts etc.) in a much more stable unit. The bank takes care of working out how much stock to transfer to make a given fiat denominated payment.
It is perfectly possible that they directly exchange stocks but denominate prices (and wages, contracts etc.) in a much more stable unit. The bank takes care of working out how much stock to transfer to make a given fiat denominated payment.