貨幣貶值，對美元來說，意味著對其他貨幣價值的下降。例如，如果一美元可以兌換一加拿大元，那麼就可以稱他們平價。如果匯率上升到一美元兌換0.85加拿大元，美元就相對加拿大元喪失價值因此相對於它貶值。一系列的經濟因素會導致美元貶值。這些因素包括貨幣政策、通脹、貨幣需求、經濟增長和出口價格。
貨幣政策
在美國，聯邦儲蓄委員會（美國的中央銀行，通常成為美聯儲），發行貨幣政策增強或者削弱美元。在最基本層面上，發行衆所週知的“寬松”貨幣政策削弱美元，這將導致美元貶值。例如，如果美聯儲降低利率或實行量化寬松措施，比如購買債券，就會被說成是在實行寬松。當銀行減少利率鼓勵投資者借款時就會產生寬松。
由於美元是法定貨幣，這就意味著它不受任何有形貨幣的支撐，可以憑空制造。當更多的貨幣被發行，供求關系的規律就會介入，使現有貨幣價值降低。
通脹
美國的通脹率和貿易夥伴的通脹率或者貨幣貶值是相反的關系。相對來說，通脹率越高貨幣價值就會越低，因為通脹意味著商品和服務的成本在增加。這些商品要比在其他國家購買更昂貴。價格上升將會降低需求。相對的，在高通脹國家進口貨物將會變得更有吸引力。
貨幣需求
當一個國家的貨幣被需求時，這種貨幣就會保持強勢。一種使貨幣保持強勢的方法就是這個國家出口產品到其他國家，其他國家願意夠買其產品並用這種貨幣付款。雖然美國的出口並不比其進口多，但是它發現了另外一條創建全球對美元人工需求的方式。
美元是所謂的儲備貨幣。儲備貨幣被全世界的國家用來購買大宗商品，例如石油和黃金。當賣方要求用儲備貨幣付款時，對這種貨幣的一個人工需求就被建立了，使這種貨幣比原來強勁。
在美國，有對中國的迅速發展使人民幣獲得儲備貨幣地位從而減少美元需求的擔心。同樣的憂慮也圍繞著石油生產國不再要求以美元付款。對美元人工需求的減少將會大幅度削減美元價值。
增長緩慢
強勁的經濟體貨幣強勁。疲軟的經濟體貨幣疲軟。經濟增長緩慢和企業收益的下降將會使投資者將資金投入到其他地方。投資者興趣的下降在特定國家將會使貨幣貶值。當貨幣投機者發現或參與到貶值中，他們會做空貨幣，使貨幣進一步貶值。
出口價格下跌
當一個關鍵出口商品的價格下降，貨幣可能會貶值。例如，加拿大元在石油價格大幅下跌時貶值，因為石油是加拿大的主要出口商品。
貿易平衡呢？
國家像人一樣，其中一些的花銷比收入大。正如每個投資者熟知的，這是不好的，因為會產生債務。在美國，進口量大於出口量，而且已經維持了幾十年。
美國維持其揮霍的財務方式的方法之一就是發行債務。中國和日本，兩個出口大量貨物到美國的國家，通過向美國大量借貸幫助美國維持赤字消費。為了換取貸款，美國發行國債券並向持有這些債券的國家支付利息。終將有一天，這些債務將會到期，借款人將會想要收回他們的資金。理論家認為如果在那時借款人認為債務水平是無法支撐的，美元將會貶值。貿易平衡也受到出口商品價格、通貨膨脹和其他因素的影響。貿易平衡變化由其他經濟因素引起，它不能引起這些因素。更深入了解這個問題,閱讀《全球經濟分析——貨幣升值和貶值》。
複雜公式
許多其他因素能夠導致美元貶值，包括政治動蕩（特定的國家或者其鄰國）、投資者行為（風險規避）和宏觀基本面疲軟。所有這些因素之間的關系複雜,所以很難證明一個孤立的因素將推動貨幣貶值。例如,央行政策被認為是貨幣貶值的重要推動力。如果美聯儲實行低利率和獨特的量化寬松計劃,人們會預計美元的價值大大削弱。但是，如果其他國家實行更強勁的貨幣寬松政策，投資者認為美國的寬松措施將要結束且外國央行的力度將會加大，美元實際上可能變強。
因此，相對於其他因素，幾種能夠導致貨幣貶值的因素必須考慮在内。這些挑戰給貨幣市場的投資者帶來了巨大的障礙，正如我們看到的在2015年國家央行突然削弱貨幣導致的瑞士法郎的價值大幅度下跌。其他關於貨幣貶值的預測，請見：《貨幣貶值》。
貨幣貶值：好還是壞？
關於貨幣貶值好還是壞的答案基本上取決於你所處的視角。如果你是一個出口公司的首席執行官，貨幣貶值對你來說就是有利的。當你國貨幣相對你出口市場的貨幣貶值，對你公司產品的需求就會增加，因為對你目標市場的消費者來說你產品的價格下降了。
相反，你的公司進口原材料生產成品，貨幣貶值對你來說就是個壞消息。貨幣貶值意味著你將花費更多成本進口原材料，這將迫使你增加你生產成品的價格(可能導致需求的下降）或者降低你的利潤。
消費者也面臨同樣的問題。美元貶值將會使去歐洲度假或者購買進口轎車更加昂貴。如果你雇主的業務由於原材料成本上升而受到損害且面臨裁員，也可能導致你的失業。相反一面，如果你的雇主的業務由於國外買家需求增加而激增，這將意味著更高的工資和更好的工作保障。
總結
大量的因素影響貨幣價值。美元是否相對於另一個國家貨幣貶值取決於兩個國家的貿易平衡、通貨膨脹率、投資者信心、政治穩定性和儲備貨幣地位。經濟學家、市場觀察人員、政治家和商業領袖都在仔細觀察不斷變化的經濟因素組合以確定美元的反映。
Top Economic Factors That Depreciate The $US
By James E. McWhinney
Currency depreciation, in the context of the U.S. dollar, refers to the decline in value of the dollar relative to another currency. For example, if one U.S. dollar can be exchanged for one Canadian dollar, the currencies are described as being at parity. If the exchange rate moves and one U.S. dollar can now be exchanged for 0.85 Canadian dollars, the U.S. dollar has lost value relative to its Canadian counterpart and has therefore depreciated against it. A variety of economic factors can contribute to depreciating the U.S. dollar. These include monetary policy, inflation, demand for currency, economic growth, and export prices.
Monetary Policy
In the United States, the Federal Reserve (the country’s central bank, usually just called the Fed), implements monetary policies to either strengthen or weaken the U.S. dollar. At the most basic level, implementation of what is known as “easy” monetary policy weakens the dollar, which can lead to depreciation. So, for example, if the Fed lowers interest rates or implements quantitative easing measures such as the purchase of bonds, it is said to be “easing.” Easing occurs when central banks reduce interest rates, encouraging investors to borrow money.
Since the U.S. dollar is a fiat currency, meaning that it is not backed by any tangible commodity (gold or silver), it can be created out of thin air. When more money is created, the law of supply and demand kicks in, making existing money less valuable.
Inflation
There is an inverse relationship between U.S. inflation rate versus its trading partners’ and currency depreciation or appreciation. Relatively speaking, higher inflation depreciates currency because inflation means that the cost of the goods and services are rising. Those goods then cost more for other nations to purchase. Rising prices decrease demand. Conversely, imported goods become more attractive for consumers in the higher inflation country to purchase.
Demand for Currency
When a country’s currency is in demand, the currency stays strong. One of the ways a currency remains in demand is if the country exports products that other countries want to buy and demands payment in its own currency. While the U.S. does not export more than it imports, it has found another way to create an artificially high global demand for U.S. dollars.
The U.S. dollar is what is known as a reserve currency. Reserve currencies are used by nations across the world to purchase desired commodities, such as oil and gold. When sellers of these commodities demand payment in reserve currency, an artificial demand for that currency is created, keeping it stronger than it might otherwise have been.
In the United States, there are fears that China’s growing interest in attaining reserve currency status for the yuan (also known as the renmimbi) will reduce demand for the U.S. dollars. Similar concerns surround the idea that oil producing nations will no longer demand payment in U.S. dollars. Reduction in the artificial demand for U.S. dollars is likely to depreciate the dollar.
Slowing Growth
Strong economies tend to have strong currencies. Weak economies tend to have weak currencies. Declining growth and corporate profits can cause investors to take their money elsewhere. Reduced investor interest in a particular country can weaken its currency. As currency speculators see or anticipate the weakening, they can bet against the currency, causing it to weaken further.
Falling Export Prices
When prices for a key export product fall, currency can depreciate. For example, the Canadian dollar (known as the loonie) weakens when oil prices drop because oil is a major export product for Canada.
What About Trade Balances?
Nations are like people. Some of them spend more than they earn. This, as every good investor knows, is a bad idea because it produces debt. In the case of the United States, the country imports more than in exports, and has done so for decades.
One of the ways the United States finances its profligate ways is by issuing debt. China and Japan, two countries that export a significant amount of goods to the United States, help finance U.S. deficit spending by loaning it massive amounts of money. In exchange for the loans, the United States issues U.S. Treasury securities (essentially IOUs) and pays interest to the nations that hold those securities. Someday, those debts will come due and the lenders will want their money back. If lenders believe the debt level is unsustainable, theorists believe the dollar will weaken. Trade balances are also impacted by export prices, inflation, and other variables. The balance of trade changes as a result of other economic factors, it does not cause those factors. For more insight into this issue, read Global Economic Analysis - Currency Appreciation and Depreciation.
A Complex Equation
A number of other factors that can contribute to dollar depreciation include political instability (either in a particular nation or sometimes in its neighbors), investor behavior (risk aversion), and weakening macroeconomic fundamentals. There is a complex relationship between all of these factors, so it can be difficult to cite a single factor that will drive currency depreciation in isolation. For example, central bank policy is considered to be a significant driver of currency depreciation. If the U.S. Federal Reserve implements low interest rates and unique quantitative easing programs, one would expect the value of the dollar to weaken significantly. However, if other nations implement even more significant easing measures and/or investors expect U.S. easing measures to stop and foreign central banks efforts to increase, the strength of the dollar may actually rise.
Accordingly, the various factors that can drive currency deprecation must be taken into consideration relative to all of the other factors. These challenges present formidable obstacles to investors who speculate in the currency markets, as was seen when the value of the Swiss franc suddenly collapsed in 2015 as a result of that nation’s central bank making a surprise move to weaken the currency. For additional insight into currency depreciation, see Currency Depreciation.
Depreciation: Good or Bad?
The question of whether currency depreciation is good or bad largely depends on perspective. If you are the chief executive officer of a company that exports its products, currency depreciation is good for you. When your nation’s currency is weak relative to the currency in your export market, demand for your products will rise because the price for them has fallen for consumers in your target market.
On the other hand, if your firm imports raw materials to produce your finished products, currency depreciation is bad news. A weaker currency means that it will cost you more to obtain the raw materials, which will force you to either increase the cost of your finished products (potentially leading to reduced demand for them) or lower your profit margins.
A similar dynamic is place for consumers. A weak dollar makes it more expensive to take that European vacation or buy that new imported car. It can also lead to unemployment if your employer’s business suffers because the rising cost of imported raw materials hurts business and forces layoffs. On the other hand, if your employer’s business surges due to increase demand from foreign buyers, it can mean higher wages and better job security.
The Bottom Line
A large number of factors influence currency value. Whether the U.S. dollar depreciates in relation to another currency depends on the monetary policies of both nations, trade balances, inflation rates, investor confidence, political stability, and reserve currency status. Economists, market watchers, politicians, and business leaders carefully monitor the ever-changing mix of economic factors in an effort to determine how the dollar reacts.
本文翻譯由兄弟財經提供
文章來源：http://www.investopedia.com/articles/forex/051115/top-economic-factors-depreciate-us.asp