货币贬值，对美元来说，意味着对其他货币价值的下降。例如，如果一美元可以兑换一加拿大元，那么就可以称他们平价。如果汇率上升到一美元兑换0.85加拿大元，美元就相对加拿大元丧失价值因此相对于它贬值。一系列的经济因素会导致美元贬值。这些因素包括货币政策、通胀、货币需求、经济增长和出口价格。
货币政策
在美国，联邦储蓄委员会（美国的中央银行，通常成为美联储），发行货币政策增强或者削弱美元。在最基本层面上，发行众所周知的“宽松”货币政策削弱美元，这将导致美元贬值。例如，如果美联储降低利率或实行量化宽松措施，比如购买债券，就会被说成是在实行宽松。当银行减少利率鼓励投资者借款时就会产生宽松。
由于美元是法定货币，这就意味着它不受任何有形货币的支撑，可以凭空制造。当更多的货币被发行，供求关系的规律就会介入，使现有货币价值降低。
通胀
美国的通胀率和贸易伙伴的通胀率或者货币贬值是相反的关系。相对来说，通胀率越高货币价值就会越低，因为通胀意味着商品和服务的成本在增加。这些商品要比在其他国家购买更昂贵。价格上升将会降低需求。相对的，在高通胀国家进口货物将会变得更有吸引力。
货币需求
当一个国家的货币被需求时，这种货币就会保持强势。一种使货币保持强势的方法就是这个国家出口产品到其他国家，其他国家愿意够买其产品并用这种货币付款。虽然美国的出口并不比其进口多，但是它发现了另外一条创建全球对美元人工需求的方式。
美元是所谓的储备货币。储备货币被全世界的国家用来购买大宗商品，例如石油和黄金。当卖方要求用储备货币付款时，对这种货币的一个人工需求就被建立了，使这种货币比原来强劲。
在美国，有对中国的迅速发展使人民币获得储备货币地位从而减少美元需求的担心。同样的忧虑也围绕着石油生产国不再要求以美元付款。对美元人工需求的减少将会大幅度削减美元价值。
增长缓慢
强劲的经济体货币强劲。疲软的经济体货币疲软。经济增长缓慢和企业收益的下降将会使投资者将资金投入到其他地方。投资者兴趣的下降在特定国家将会使货币贬值。当货币投机者发现或参与到贬值中，他们会做空货币，使货币进一步贬值。
出口价格下跌
当一个关键出口商品的价格下降，货币可能会贬值。例如，加拿大元在石油价格大幅下跌时贬值，因为石油是加拿大的主要出口商品。
贸易平衡呢？
国家像人一样，其中一些的花销比收入大。正如每个投资者熟知的，这是不好的，因为会产生债务。在美国，进口量大于出口量，而且已经维持了几十年。
美国维持其挥霍的财务方式的方法之一就是发行债务。中国和日本，两个出口大量货物到美国的国家，通过向美国大量借贷帮助美国维持赤字消费。为了换取贷款，美国发行国债券并向持有这些债券的国家支付利息。终将有一天，这些债务将会到期，借款人将会想要收回他们的资金。理论家认为如果在那时借款人认为债务水平是无法支撑的，美元将会贬值。贸易平衡也受到出口商品价格、通货膨胀和其他因素的影响。贸易平衡变化由其他经济因素引起，它不能引起这些因素。更深入了解这个问题,阅读《全球经济分析——货币升值和贬值》。
复杂公式
许多其他因素能够导致美元贬值，包括政治动荡（特定的国家或者其邻国）、投资者行为（风险规避）和宏观基本面疲软。所有这些因素之间的关系复杂,所以很难证明一个孤立的因素将推动货币贬值。例如,央行政策被认为是货币贬值的重要推动力。如果美联储实行低利率和独特的量化宽松计划,人们会预计美元的价值大大削弱。但是，如果其他国家实行更强劲的货币宽松政策，投资者认为美国的宽松措施将要结束且外国央行的力度将会加大，美元实际上可能变强。
因此，相对于其他因素，几种能够导致货币贬值的因素必须考虑在内。这些挑战给货币市场的投资者带来了巨大的障碍，正如我们看到的在2015年国家央行突然削弱货币导致的瑞士法郎的价值大幅度下跌。其他关于货币贬值的预测，请见：《货币贬值》。
货币贬值：好还是坏？
关于货币贬值好还是坏的答案基本上取决于你所处的视角。如果你是一个出口公司的首席执行官，货币贬值对你来说就是有利的。当你国货币相对你出口市场的货币贬值，对你公司产品的需求就会增加，因为对你目标市场的消费者来说你产品的价格下降了。
相反，你的公司进口原材料生产成品，货币贬值对你来说就是个坏消息。货币贬值意味着你将花费更多成本进口原材料，这将迫使你增加你生产成品的价格(可能导致需求的下降）或者降低你的利润。
消费者也面临同样的问题。美元贬值将会使去欧洲度假或者购买进口轿车更加昂贵。如果你雇主的业务由于原材料成本上升而受到损害且面临裁员，也可能导致你的失业。相反一面，如果你的雇主的业务由于国外买家需求增加而激增，这将意味着更高的工资和更好的工作保障。
总结
大量的因素影响货币价值。美元是否相对于另一个国家货币贬值取决于两个国家的贸易平衡、通货膨胀率、投资者信心、政治稳定性和储备货币地位。经济学家、市场观察人员、政治家和商业领袖都在仔细观察不断变化的经济因素组合以确定美元的反映。
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.
本文翻译由兄弟财经提供
文章来源：http://www.investopedia.com/articles/forex/051115/top-economic-factors-depreciate-us.asp