本世纪70年代初，世界各主要货币国家纷纷改用浮动汇率制。这一变动意味着：如果一个国际企业的外汇帐户留有开放的头寸，那么其面临的外汇风险就大大增加了。为了减避外汇风险、或者利用汇率变动差价达到外币投机套利目的，现在已有越来越多国家的国际企业在国际金融市场上开 The early 70s of this century, the world’s major currency countries have switched to floating exchange rate system. This change means that if an international firm’s foreign exchange account has an open position, the foreign exchange risk it faces is greatly increased. In order to avoid foreign exchange risk or to use the spread of exchange rate changes to achieve the purpose of foreign currency speculative arbitrage, more and more countries now have their international enterprises open in international financial markets