Dislikedwhat do you mean by ALLOW to happen? Currency markets are driven by supply and demand, not by somebody saying yes it is allowed to go down or up. Maybe in the short-term huge banks can control one of the currencies, but after a week it will go where supply and demand says it has to go.Ignored
Also, another good case is the CHINESE government and their currency: the renminbi. The chinese exhibits very strong monetary control policy, leaving their yuan to fluctuates only within narrow bands, severely preventing from appreciating against the dollar....because appreciating yuan will delimit their exporting power. That is definitely not a result of supply and demand, it is a result of artificial market ceiling created by the chinese government.
True, we do have exceptions like the case of SOROs that broke the bank of england....