美国在制造一个可怕的泡沫

　　Since March there has been a massive rally in all sorts of risky assets – equities, oil, energy and commodity prices – a narrowing of high-yield and high-grade credit spreads, and an even bigger rally in emerging market asset classes (their stocks, bonds and currencies). At the same time, the dollar has weakened sharply, while government bond yields have gently increased but stayed low and stable.
　　自今年3月以来，各类高风险资产——股票、石油、能源和大宗商品——的价格一直在强劲上扬，高收益和高等级信贷的息差一直在收窄，新兴市场资产类别（新兴市场股票、债券和货币）的上涨幅度则更大。与此同时，美元汇率大幅下挫，国债收益率缓慢上升，但仍维持在低位并保持稳定。

　　This recovery in risky assets is in part driven by better economic fundamentals. We avoided a near depression and financial sector meltdown with a massive monetary, fiscal stimulus and bank bail-outs. Whether the recovery is V-shaped, as consensus believes, or U-shaped and anaemic as I have argued, asset prices should be moving gradually higher.
　　在一定程度上，高风险资产的复苏是由经济基本面改善推动的。凭借大规模的货币、财政刺激和对银行的纾困，我们避免了一场近乎萧条的灾难和金融业危机。不管这场复苏是V型的（就像人们普遍认为的那样），还是U型和无力的（就像我所主张的那样），资产价格都应逐渐上行。

　　But while the US and global economy have begun a modest recovery, asset prices have gone through the roof since March in a major and synchronised rally. While asset prices were falling sharply in 2008, when the dollar was rallying, they have recovered sharply since March while the dollar is tanking. Risky asset prices have risen too much, too soon and too fast compared with macroeconomic fundamentals.
　　然而，当美国经济和全球经济刚刚开始温和复苏时，资产价格已经在自今年3月开始的一轮较大的同步上涨行情中一路飙升。尽管资产价格曾在2008年大幅下跌（美元汇率当时则出现上扬），但自今年3月以来，资产价格已大幅回升，而同时美元却在下跌。相对于宏观基本面而言，高风险资产的价格上涨得过早、过快，涨幅也过大。

　　So what is behind this massive rally? Certainly it has been helped by a wave of liquidity from near-zero interest rates and quantitative easing. But a more important factor fuelling this asset bubble is the weakness of the US dollar, driven by the mother of all carry trades. The US dollar has become the major funding currency of carry trades as the Fed has kept interest rates on hold and is expected to do so for a long time. Investors who are shorting the US dollar to buy on a highly leveraged basis higher-yielding assets and other global assets are not just borrowing at zero interest rates in dollar terms; they are borrowing at very negative interest rates – as low as negative 10 or 20 per cent annualised – as the fall in the US dollar leads to massive capital gains on short dollar positions.
　　那么资产价格大幅上涨的原因是什么呢？当然，这受益于由近零利率和定量宽松政策带来的一波流动性。但助长这轮资产泡沫的一个更重要的因素，是由所有利差交易之源动力造成的美元疲软。美元已成为利差交易的主要融资货币，因为美联储(Fed)一直维持利率不变，并预计将长期不作调整。那些做空美元、以很高的杠杆买入高收益资产和其它全球性资产的投资者，岂止是在以零利率借入美元；他们简直是在以负利率（年化利率为-10%或-20%）借入美元，因为美元汇率的下跌会使美元空头头寸产生巨额资本收益。

　　Let us sum up: traders are borrowing at negative 20 per cent rates to invest on a highly leveraged basis on a mass of risky global assets that are rising in price due to excess liquidity and a massive carry trade. Every investor who plays this risky game looks like a genius – even if they are just riding a huge bubble financed by a large negative cost of borrowing – as the total returns have been in the 50-70 per cent range since March.
　　我们来总结一下吧：交易员正以-20%的利率借入资金，并以很高的杠杆投资于众多高风险全球资产——由于流动性过剩和大规模利差交易，这些资产的价格正在上涨。所有玩这种高风险游戏的投资者看上去都像是天才——尽管他们只不过是骑在一个由（绝对值）较高的负借款成本融资的巨大泡沫上——自今年3月以来，他们的总回报率已达到50%至70%。

　　People's sense of the value at risk (VAR) of their aggregate portfolios ought, instead, to have been increasing due to a rising correlation of the risks between different asset classes, all of which are driven by this common monetary policy and the carry trade. In effect, it has become one big common trade – you short the dollar to buy any global risky assets.
　　人们原本应该愈发强烈的感知到自己总投资组合的风险价值(VaR)，因为不同资产类别之间的风险相关度一直在上升——所有这些资产的走势全是由同一货币政策以及利差交易推动的。实际上，它已变成一项大规模的共同交易：做空美元、买入任何类别的全球高风险资产。

　　Yet, at the same time, the perceived riskiness of individual asset classes is declining as volatility is diminished due to the Fed's policy of buying everything in sight – witness its proposed $1,800bn (£1,000bn, €1,200bn) purchase of Treasuries, mortgage- backed securities (bonds guaranteed by a government-sponsored enterprise such as Fannie Mae) and agency debt. By effectively reducing the volatility of individual asset classes, making them behave the same way, there is now little diversification across markets – the VAR again looks low.
　　但与此同时，各个资产类别的可感知风险却在下降。其原因是，美联储购买一切可见资产的政策降低了波动性。例如，美联储拟购买1.8万亿美元国债、抵押贷款支持证券（由房利美(Fannie Mae)等政府支持企业担保的债券）和机构债务。通过有效降低各个资产类别的波动性、令其走势趋同，市场多样化现在几乎已经消失，风险价值似乎再次处于低位。

　　So the combined effect of the Fed policy of a zero Fed funds rate, quantitative easing and massive purchase of long-term debt instruments is seemingly making the world safe – for now – for the mother of all carry trades and mother of all highly leveraged global asset bubbles.
　　因此，对所有利差交易和高杠杆全球资产泡沫的源动力而言，美联储的零利率、定量宽松政策以及大规模购买长期债务工具的综合效应，似乎正在令世界变得安全起来（目前来看如此）。

　　While this policy feeds the global asset bubble it is also feeding a new US asset bubble. Easy money, quantitative easing, credit easing and massive inflows of capital into the US via an accumulation of forex reserves by foreign central banks makes US fiscal deficits easier to fund and feeds the US equity and credit bubble. Finally, a weak dollar is good for US equities as it may lead to higher growth and makes the foreign currency profits of US corporations abroad greater in dollar terms.
　　这种政策助长了全球资产泡沫，同时也在助长美国新一轮的资产泡沫。廉价资金、定量宽松、放宽信贷，再加上以外国央行累积外汇储备的形式流入美国的巨额资金，令美国财政赤字的融资变得更为容易，并助长了美国股市和信贷泡沫。最后，美元的疲软也在支撑美国股市，因为它可能会带来更高的增长，而且让美国公司的外币利润换算成美元时可以显得更多。

　　The reckless US policy that is feeding these carry trades is forcing other countries to follow its easy monetary policy. Near-zero policy rates and quantitative easing were already in place in the UK, eurozone, Japan, Sweden and other advanced economies, but the dollar weakness is making this global monetary easing worse. Central banks in Asia and Latin America are worried about dollar weakness and are aggressively intervening to stop excessive currency appreciation. This is keeping short-term rates lower than is desirable. Central banks may also be forced to lower interest rates through domestic open market operations. Some central banks, concerned about the hot money driving up their currencies, as in Brazil, are imposing controls on capital inflows. Either way, the carry trade bubble will get worse: if there is no forex intervention and foreign currencies appreciate, the negative borrowing cost of the carry trade becomes more negative. If intervention or open market operations control currency appreciation, the ensuing domestic monetary easing feeds an asset bubble in these economies. So the perfectly correlated bubble across all global asset classes gets bigger by the day.
　　美国这种不计后果的政策助长了这类利差交易，迫使其它国家仿效其宽松的货币政策。英国、欧元区、日本、瑞典和其它发达经济体已经施行了近零利率及定量宽松政策，但美元的疲软正在加剧这一全球货币宽松局面。亚洲和拉美的央行对美元疲软感到担忧，它们正大举干预，阻止本币升值过高。这使得短期利率保持在低于理想值的水平上。此外，各国央行还可能被迫通过国内公开市场操作来下调利率。一些担心热钱正推升本币汇率的央行（如巴西央行），正对资本流入施加管控措施。不管是哪种情况，利差交易泡沫都将恶化：如果不实施外汇干预，并且外币又在升值，那么利差交易的负借款成本将变成一个绝对值更高的负值。如果外汇干预或公开市场操作控制住了本币的升值，那么由此引发的国内货币宽松局面就将助长这些经济体的资产泡沫。因此，这个存在于各个全球资产类别中的、完全相关的泡沫将变得越来越大。

　　But one day this bubble will burst, leading to the biggest co-ordinated asset bust ever: if factors lead the dollar to reverse and suddenly appreciate – as was seen in previous reversals, such as the yen-funded carry trade – the leveraged carry trade will have to be suddenly closed as investors cover their dollar shorts. A stampede will occur as closing long leveraged risky asset positions across all asset classes funded by dollar shorts triggers a co-ordinated collapse of all those risky assets – equities, commodities, emerging market asset classes and credit instruments.
　　但总有一天这个泡沫会破裂，并引发一场有史以来规模最大的、协同性的资产崩盘：如果相关因素导致美元走势逆转并突然升值——就像我们在前几次逆转（例如日元融资的利差交易）中看到的那样——杠杆化的利差交易将不得不在很短时间内平仓，因为投资者需要回补其美元空头头寸。投资者将大举溃退，因为对所有由美元融资的资产类别的杠杆化高风险资产多头头寸进行平仓，将引发所有高风险资产（股票、大宗商品、新兴市场资产类别及信贷工具）的协同性崩盘。

　　Why will these carry trades unravel? First, the dollar cannot fall to zero and at some point it will stabilise; when that happens the cost of borrowing in dollars will suddenly become zero, rather than highly negative, and the riskiness of a reversal of dollar movements would induce many to cover their shorts. Second, the Fed cannot suppress volatility forever – its $1,800bn purchase plan will be over by next spring. Third, if US growth surprises on the upside in the third and fourth quarters, markets may start to expect a Fed tightening to come sooner, not later. Fourth, there could be a flight from risk prompted by fear of a double dip recession or geopolitical risks, such as a military confrontation between the US/Israel and Iran. As in 2008, when such a rise in risk aversion was associated with a sharp appreciation of the dollar, as investors sought the safety of US Treasuries, this renewed risk aversion would trigger a dollar rally at a time when huge short dollar positions will have to be closed.
　　为何这类利差交易会平仓？首先，美元汇率不可能降至零，它终将在某一水平企稳；这时，美元的借入成本将突然变成零，而不是绝对值很高的负值，美元走势逆转的风险将促使许多人回补其美元空头头寸。其次，美联储不可能永远抑制波动性，其1.8万亿美元的购买计划将于明年春季结束。第三，如果美国第三和第四季度的经济增长数据好于预期，那么市场可能会开始预测，美联储将更早（而不是更晚）收紧银根。第四，人们对双底衰退或地缘政治风险的担忧可能会引发避险行为，后者如美国-以色列与伊朗之间的军事对峙。就像2008年那样，在大量美元空头头寸不得不平仓之时，这类重新出现的避险情绪将引发一波美元上涨行情。2008年时，由于投资者转向美国国债寻求庇护，避险情绪的上升就与美元的大幅升值建立起联系。

　　This unraveling may not occur for a while, as easy money and excessive global liquidity can push asset prices higher for a while. But the longer and bigger the carry trades and the larger the asset bubble, the bigger will be the ensuing asset bubble crash. The Fed and other policymakers seem unaware of the monster bubble they are creating. The longer they remain blind, the harder the markets will fall.
　　这种平仓行为可能暂时不会出现，因为廉价资金和全球流动性过剩可能会暂时推升资产价格。但是，利差交易持续的时间越长、规模越大，同时资产泡沫变得越大，那么随后资产泡沫破裂的规模也就越大。美联储和其它政策制定者似乎没有意识到，他们正在制造一个极其可怕的泡沫。他们无视于此的时间越长，市场未来下跌得就越惨。

　　The writer is a professor at New York University's Stern School of Business and chairman of Roubini Global Economics
　　本文作者是美国纽约大学(New York University)斯特恩商学院(Stern School of Business)教授、鲁比尼全球经济咨询公司(Roubini Global Economics)董事长
　　
　　译者/梁艳裳