Buck up 振作起来

2020.10


Global trade’s dependence on dollars lessens its benefits
全球贸易对美元的依赖减少了它的益处【“反思经济学基本理论”系列之六】 

 

Buck up 振作起来 - 经济学人


English placeholder caption CRASHING CURRENCIES hurt. They make imports more expensive, cutting into household budgets and raising businesses’ costs. But economics has long held that this pain brings with it its own salve. More expensive imports should drive new demand for home-made replacements and thus for the workers who make them, geeing up the economy. What is more, a devalued currency means exports are suddenly cheaper to buyers abroad. That, too, should boost demand. When the value of the Colombian peso collapsed in the summer of 2014, it was on the basis of these assumptions that the country’s finance minister greeted the fall as “a blessing in disguise”.
崩溃的货币让人受伤。这会让进口商品变得更加昂贵,消耗家庭预算并增加企业的成本。但是经济学长期以来一直认为,这种痛楚自带解药。进口商品昂贵将推动对本国替代品的新需求,由此推动对生产它们的工人的需求,从而刺激经济。更重要的是,货币贬值意味着面向国外买家的出口价格突然便宜了。这应该也会刺激需求。当哥伦比亚比索的价值在2014年夏天暴跌时,正是基于这些假设,该国财政部长才将这次下跌视为“因祸得福”。
It wasn’t. There were, the IMF opined in a subsequent report, a number of reasons for this, many specific to Colombia. But one problem was a factor which is embedded in the machinery of today’s international commerce. Colombia does not trade in pesos. It trades almost exclusively in dollars; 98% of its exports are invoiced in them. This is an extreme example of a general point. The amount of trade carried out in American dollars vastly exceeds the amount that America imports and exports. Although that may seem like a detail of book-keeping, it matters a lot. A growing body of evidence suggests that the dollar’s prominence in trade undermines the advantages which flexible exchange rates are meant to offer. And when the dollar strengthens, global trade tends to contract.
然而事与愿违。国际货币基金组织(以下简称IMF)在随后的报告中指出,这背后有许多原因,其中许多是哥伦比亚所特有的。但是,其中一个问题是当今国际贸易机制中固有的一个因素。哥伦比亚并不以比索开展贸易,而是几乎只用美元交易;其中98%的出口都以美元开票。这虽是个极端例子,却说明了普遍的问题。以美元进行的贸易额大大超过了美国的进出口额。尽管这看似是簿记中的一个细节,却影响深远。越来越多的证据表明,美元在贸易中的突出地位削弱了灵活汇率本应带来的好处。而当美元走强时,全球贸易趋于收缩。
For decades, economists’ thinking about trade and currencies was summarised in a model created in the 1960s by two researchers at the IMF, Robert Mundell and J. Marcus Fleming. They assumed no special role for any dominant currency, but rather that traders would agree on prices in the exporter’s currency. A Colombian devaluation, say, would immediately turn peso-priced batteries into bargains abroad, encouraging foreign buyers to scoop up more of them. Meanwhile shoppers in Bogotá wanting to buy Brazilian T-shirts would resent being made to fork out more pesos to cover the price fixed in real.
曾有几十年,经济学家对贸易和货币的思考都被总结到了IMF的两位研究人员罗伯特•蒙代尔(Robert Mundell)和马库斯•弗莱明(J. Marcus Fleming)在1960年代创建的模型中。他们没有假定任何主导货币会承担什么特殊的角色,而是假定交易者会就以出口方货币计价的价格达成一致。比方说,哥伦比亚的货币贬值将立即使以比索定价的电池成为外国眼中的便宜货,从而鼓励外国买家购买更多的电池。同时,想要购买巴西T恤衫的波哥大购物者会因为被迫掏出更多比索来买以巴西雷亚尔标价的衣服而感到不满。 This simplifying assumption was potentially consequential. As early as 1947, Joan Robinson of the University of Cambridge noted that the currency companies used for invoicing could mute the expenditure-switching effect. If the prices of Colombian exports were in dollars, not pesos, a devaluation would leave prices faced by American importers—and their demand—unaffected. But though that might matter in principle, did it matter much in practice?
这种简化的假设很可能影响深远。早在1947年,剑桥大学的琼•罗宾逊(Joan Robinson)指出,公司开票时所用的货币可能会削弱这种支出转移效应。如果哥伦比亚出口商品的价格是以美元而不是比索计价,那么比索贬值并不会影响美国进口商面临的价格及其需求。但是,尽管从原则上讲这可能很重要,但在实践中会有很大关系吗?
In 1973 Sven Grassman of the Institute for International Economic Studies used Swedish data to answer in the negative. He found that in 1968 around two-thirds of Swedish trade had been indeed invoiced in the currency of the exporter. This “fundamental symmetry in international payment patterns” became known as “Grassman’s Law”. Swedish exports to America, which were mostly invoiced in dollars not kronor, were written off as the exception. That suggested that Mundell and Fleming were right.
国际经济研究所的斯文•格拉斯曼(Sven Grassman)在1973年使用瑞典的数据做出了否定的回答。他发现在1968年,瑞典有约三分之二的贸易确实是以出口商的货币开票的。这种“国际支付模式的基本对称性”被称为“格拉斯曼定律”。瑞典对美国的出口大多以美元而非克朗开票,这被认为是例外情况。这表明蒙代尔和弗莱明是正确的。
Over the next decades more data further supported Grassman’s Law—always with the same American exception. But by the 1990s some researchers were beginning to doubt its validity. Their main argument was that the actual prices of goods did not vary as much or as quickly as would be expected if payments were in fact symmetrical. Grassman’s Law said that the price of Brazilian T-shirts in Colombian markets should vary with the peso-real exchange rate, for example. But such prices were in fact much stickier.
在接下来的几十年中,更多的数据进一步支持了“格拉斯曼定律”,而美国一直是例外。但是,到了1990年代,一些研究人员开始怀疑这条定律的有效性。他们的主要论据是,商品的实际价格变化并不像支付货币真的对称时那样大或那样快。比如,格拉斯曼定律认为哥伦比亚市场上的巴西T恤衫的价格应随比索和雷亚尔的汇率变化。但是实际上这些价格的粘性要大得多。
In the mid-2000s Linda Goldberg and Cedric Tille of the Federal Reserve Bank of New York compiled data describing 24 countries in the late 1990s and early 2000s. This confirmed that Grassman’s Law was wrong: exports were not generally priced in the currency of the country they came from. In 2001, for example, they found that South Korea invoiced 82% of its imports in dollars, despite only 16% of its imports coming from America.
在2000年代中期,纽约联邦储备银行的琳达•戈德堡(Linda Goldberg)和塞德里克•蒂尔(Cedric Tille)编制的数据描述了1990年代末到2000年代初的24个国家。它证实了格拉斯曼定律是错误的:出口通常不以其来源国的货币计价。例如,在2001年,他们发现,韩国有82%的进口以美元开票,尽管其中只有16%来自美国。
Other work confirmed and updated their findings: the dollar has a huge role as a “vehicle currency” in which to invoice transactions to which no Americans are party, particularly in developing countries (see chart). Gita Gopinath of the IMF has compiled data covering just over half of world trade to show that the dollar’s share of invoicing was 4.7 times larger than America’s share of the value of imports, and triple its share of world exports. Another IMF study showed that the dollar’s share has not decreased in step with America’s declining share of overall trade.
其他研究也证实并更新了他们的发现:在那些没有美国人参与的交易中,美元作为“周转货币”用于开票的职责重大,特别是在发展中国家(见图表)。IMF的吉塔•戈皮纳特(Gita Gopinath)汇编了涵盖全球贸易一半略多的数据,显示以美元开票的比例比美国占全球进口的比例高4.7倍,是其占全球出口比例的三倍。该组织的另一项研究表明,美元所占份额并未随美国在整体贸易中所占份额的下降而同步下降。 
English placeholder caption The euro’s creators had hoped that it might supplant the dollar’s status. But even though almost half of trade is invoiced in euros, that is mostly because of how much trade involves countries that use the currency. Between 1999 and 2014 euro-denominated trade was only around 1.2 times the euro zone’s share of global imports.
欧元的创造者曾希望它能取代美元的地位。但是,即使将近一半的贸易以欧元计价,这主要是因为有许多贸易涉及使用该货币的国家。在1999年至2014年间,以欧元计价的贸易份额仅是欧元区占全球进口份额的1.2倍左右。
Other would-be challengers appear to have failed even more miserably. Scant Chinese data suggest that in 2013 only 17% of Chinese trade was settled in renminbi, and in 2012 only around half of such settlements were invoiced in renminbi. In order to avoid financial sanctions, Russia has recently shifted away from the dollar when paying for imports from China. But the euro, not the renminbi, benefited most.
其他可能的挑战者似乎败得更惨。零星的中国数据表明,2013年中国贸易中只有17%是用人民币结算的,而在2012年,此类结算中只有大约一半是用人民币开票的。为了避免金融制裁,俄罗斯最近在支付从中国进口的商品时已经不再用美元了。但是,受益最大的是欧元,而不是人民币。
A lack of historical data makes it impossible to say whether Grassman’s Law held in the 1970s and has since weakened or whether it was the always an artefact of insufficient data. Whichever is true, economists busied themselves trying to work out why exporters used dominant currencies.
由于历史数据缺乏,很难说格拉斯曼定律是不是在1970年代时成立而之后被削弱了,还是说它始终是数据不足的产物。无论如何,经济学家忙于弄清楚为什么出口商要使用主导货币。
One suggestion is that using the same vehicle currency when setting prices for a certain market lets companies avoid erratic price movements relative to their competitors. Ms Goldberg and Mr Tille offered some support for this when they showed that dollar invoicing was more common in markets, such as precious metals, where competition is cut-throat. Another suggestion is that the rise of global supply chains saw more exporters importing some inputs. Invoicing imports and exports in the same currency would preserve their profit margins in the event of a devaluation.
一个说法是,为特定市场设定价格时使用相同的周转货币,可使公司避免相对于其竞争对手的价格波动。戈德堡和蒂尔为这种说法提供了一些支持,提出在贵金属等竞争激烈的市场中以美元开票更为普遍。另一个说法是,全球供应链的兴起使更多出口商要去进口一些原材料和零部件。以同种货币对进出口开票可在货币贬值时保持利润率。 The arguments for a vehicle currency do not necessarily mean that that currency has to be the dollar. But why would it not be? The dollar already dominates the financial world. Central banks stash 58% of their official foreign-exchange reserves in it. It is the global currency of choice when issuing securities. Banks use it for around half of their cross-border claims. According to SWIFT, a payments system, it is used in two-fifths of international payments.
关于周转货币的论点并不一定意味着这种货币必须是美元。但为什么不呢?美元已经主导了金融世界。中央银行将官方外汇储备的58%存放在其中。它是发行证券时的首选全球货币。银行将它用于大约一半的跨国债权。根据付款系统SWIFT的说法,五分之二的国际付款都使用美元。
Indeed the worlds of finance and trade are intertwined. Exporters borrowing in dollars will want to price their foreign sales in the same currency, to protect against a sudden devaluation which would increase the value of their debt. Assets denominated in dollars offer their owners more security, because they will hold their value relative to imports priced in dollars.
实际上,金融和贸易世界是相互交织的。以美元借款的出口商会希望以同一货币对国外销售定价,以防本币突然贬值而增加债务价值。以美元计价的资产为所有者提供了更大的安全性,因为它们相对于以美元计价的进口产品可以保值。
Having established the importance of dollar dominance for global trade, economists updated their understanding of exchange-rate gyrations. In America sticky prices set in dollars mean the demand for imports is impervious to exchange-rate shocks. A Colombian light aircraft priced at $50,000 will cost the same when the dollar is worth 3,000 pesos as when it is worth 4,000. The change will eventually have an effect—but it will be partial, and slow. One study has found that two years after an exchange-rate shift only 44% of its effect would be seen in prices in America. Another found that just as prices did not change much, neither did the volumes importers chose to buy. After a 1% dollar depreciation, they found that the volume of imports into America fell by a measly 0.003%.
在确立美元主导地位对全球贸易的重要性之后,经济学家们更新了对汇率波动的理解。在美国,以美元定价的粘性价格意味着进口需求不受汇率冲击的影响。一架定价为50,000美元的哥伦比亚轻型飞机,不管1美元是值3000比索还是值4000比索,价格都是一样的。这种改变最终还是会产生影响——但只是部分影响,而且是缓慢的。一项研究发现,汇率变动两年后,在美国的价格中只能看到影响的44%。另一项研究发现,就像价格没有太大变化一样,进口商选择购买的数量变化也不大。在美元贬值1%之后,他们发现美国的进口量仅下降了0.003%。
Money, money, money
钱钱钱
All this allows America to enjoy what Ms Gopinath describes as a “privileged insularity”. Its adjustment to a dollar depreciation happens almost entirely through exports, which immediately become cheaper in foreign markets. Devaluations against the dollar in other countries, by contrast, see them suffer. It becomes harder to afford imports while they don’t get the added export oomph the old models suggested. Exporters’ dollar earnings will be worth more in local currency, which might tempt some of them to expand. But that takes time. And the benefits are often offset by the higher cost of imported inputs.
所有这些使美国能够享受戈皮纳特所说的“特权孤立”。它对美元贬值的调整几乎完全通过出口实现,因为出口品会立即在国外市场上变得便宜。相比之下,其他国家兑美元的贬值则使它们遭受损失。进口商品更加难以负担,却又无法像旧模型显示的那样提升出口的吸引力。出口商的美元收入可以换取更多本地货币,这可能会诱使其中一些人扩大规模。但这需要时间。而且收益通常被进口原材料上升的成本所抵消。
Around the world invoicing imports in dollars means that it is devaluations against the greenback, rather than against the currency of the country you are trading with, that count. Emine Boz of the IMF, Ms Gopinath and Mikkel Plagborg-Muller of Princeton University found that prices of imported goods were relatively unresponsive to bilateral exchange-rate movements. Over short-term horizons they were six times more sensitive to the dollar exchange rate. The price of Brazilian-made football shirts in Mexico will stay the same if the peso depreciates relative to the real, but not relative to the dollar. If the peso drops with respect to the dollar, though, those shirts will become less affordable and may no longer be sold.
在世界范围内,进口商品以美元开票意味着重要的是对美元的贬值,而不是对交易对手国货币的贬值。IMF的埃米恩•博兹(Emine Boz)、普林斯顿大学的戈皮纳特女士和米克尔•普拉格伯格-穆勒(Mikkel Plagborg-Muller)发现,进口商品的价格相对来说对双边汇率变动的反应不大。在短期内,它们对美元汇率的敏感度要高出六倍。如果比索相对于雷亚尔贬值,而不是相对于美元贬值,那么巴西生产的足球衫在墨西哥的价格将保持不变。但是,如果比索兑美元汇率下跌,那些墨西哥人可能会买不起这些运动衫,它们可能会停售。
During the East Asian crisis of 1997-99 South Korea, Malaysia and Thailand all experienced currency depreciations of at least 60% relative to the dollar—and saw their export volumes stagnate or fall. With prices set in dollars devaluations did nothing for their export competitiveness within the region. And demand for imports from elsewhere in the region—also priced in dollars—plunged. Ms Boz and her co-authors have found that, after accounting for the business cycle, a 1% appreciation in the value of the dollar translates into a 0.6% decrease in the volume of trade between countries in the rest of the world.
在1997­至1999年的东亚危机期间,韩国、马来西亚和泰国都经历了相对于美元至少60%的货币贬值,而其出口额却停滞或下降了。由于价格以美元计价,贬值对它们在该地区的出口竞争力没有任何帮助。而从该地区其他地方进口的需求(也以美元计价)则暴跌。博兹等人发现,在考虑了经济周期之后,美元价值升值1%意味着世界其他国家和地区间的贸易额下降0.6%。
Dollar dominance means trade is vulnerable to the global financial cycle, too. A study by Valentina Bruno and Hyun Song Shin of the Bank for International Settlements found that a dollar appreciation leads banks reliant on dollar funding to shrink their credit supply. Companies reliant on those banks—and their dollar-denominated financing of trade—then slow their exports, an effect particularly marked in companies with longer supply chains. Trade is a finance-hungry business.
美元的主导地位也意味着贸易容易受到全球金融周期的影响。国际清算银行的瓦伦蒂娜•布鲁诺(Valentina Bruno)和申铉松(Hyun-Song Shin)的研究发现,美元升值导致依赖美元资金的银行缩减信贷供应。然后依靠这些银行以及以美元计价的贸易融资的那些公司就放慢了出口速度,这种影响在供应链较长的公司中尤为明显。贸易是一项对融资十分饥渴的业务。
Policymakers around the world yearn to be free of the dollar’s grip. That seems unlikely. The dollar’s dominance is the product of millions of individual decisions, each seemingly optimal, which in concert lead to collective problems. Each dip in the dollar’s value leads to a rush of wishful chatter about the dollar’s demise, but for long as these optimisations continue to make sense it is hard to see how that wish can come true. At least, though, for a while, the chatter-inducing weakness will provide a fillip to trade.
全世界的决策者都渴望摆脱美元的束缚。这似乎不太可能。美元的主导地位是数以百万计的个别决定的产物,每个决定似乎都是最优的,而这共同导致了集体问题。美元价值每下跌一次,都会引起一阵关于美元垮台的一厢情愿的议论。但是只要这些优化都还说得通,就很难看到这种愿望如何能够实现。不过至少在一段时间里,这种引发议论的美元弱势还能给贸易带来一丝刺激。