Due the vast amount of money involved, and other characteristics, it is impossible for any person or company to have a major influence on the market.
Past experience shows us that even when central banks interfered with the foreign exchange market, they had success only in the short term. They usually failed in achieving their goals when they put a big foot in the market.
Contrary to stocks, a pair of currencies cannot be manipulated by a small of group of people with interests. There are so many players, and so much money, that this cannot be achieved.