The so-called "commodity currency" refers to the currency of the major net exporters of bulk commodities. The currencies of Australia, Canada, New Zealand and Norway are all "commodity currencies". In the past three months, the exchange rate against the US dollar only fell by about 3%-4%, while Brent crude oil price fell by 26%, thermal coal price fell by 18%, and copper price fell by 12%. This phenomenon is called "extreme dislocation" by Deutsche Bank analysts. The trend of commodity currency is seriously inconsistent with the price of raw materials. Unfortunately, hedge funds that bet on the weakness of commodity currencies. The negative impact of this phenomenon on net commodity exporting countries is that the production cost denominated in domestic currency has not decreased, while the income denominated in US dollars has shrunk due to falling prices. One of the explanations for this phenomenon is that investors pursue interest income. At present, the interest income of commodity currency is the highest among major industrial countries. At present, Australia's real interest rate is still higher than zero, and the nominal interest rate is 3.5%, which is the highest among all industrial countries. This can partly explain why the Australian dollar remained strong after the RBA cut interest rates. Derek Sammann, head of currency and interest rate products at the Chicago Mercantile Exchange Group, pointed out that the trading volume of the Australian dollar has recently reached a new high. Another explanation is that the main net exporters of bulk commodities are AAA countries. In the context of the worsening European debt crisis, investors and central banks are trying to find assets to replace the euro. The New Zealand dollar has risen in recent weeks after Moody's confirmed New Zealand's AAA rating at the end of May. Australia, Canada and Norway are also rare industrial countries with AAA rating. This is especially important for conservative investors such as foreign exchange reserve managers and pension funds, because one of their important missions is to seek the safest assets. Mansoor Mohi-uddin, an analyst at UBS Group AG, pointed out, "Since the new round of downgrade of euro zone member countries began at the beginning of this year, central banks have shifted their assets to the national debt of other 3A countries." Although dollar and euro assets are still the main reserve varieties of central banks, almost all central banks are seeking diversification of foreign exchange reserves. Russia and the Czech Republic recently announced the inclusion of the Australian dollar in foreign exchange reserves. Foreign exchange traders said that the New Zealand dollar and the currencies of Scandinavian countries also attracted the attention of foreign exchange reserve managers.