欧元区债券市场一片活跃，中国的负债水平创下历史新高，而美国的股市尽管上周遭受重创，总体而言仍处于大牛市中。
经济学家和政界人士对世界范围内的央行大力施压，希望它们继续乃至升级当前极为宽松的货币政策，以便刺激全球需求。然而，与此同时，这些措施或将引发又一轮市场动荡的担忧正在蔓延。
“上次危机的一大教训就是，宽松的货币政策会助长金融过剩，”曾担任欧洲央行（European Central Bank，简称ECB）副行长的卢卡斯·帕帕季莫斯(Lucas Papademos)说。“我们目前有很好的理由来追求类似的政策。但凡事有极限——假如持续时间太长，金融市场的风险就会冒出来。”
上周的时候，有关这一问题的辩论在华盛顿展开：不仅出现在智库的讨论会上、在恢弘的IMF大楼内外举办的会议里，还出现在各国政府官员与央行高层的正式对话中。
周六，ECB行长马里奥·德拉吉(Mario Draghi)附和了这种担忧。他表示，除了全球经济，讨论的一大主题是投资者“承担的金融风险日趋扩大”，尤其是非银行机构。
在某种程度上，IMF对欧元区经济——尤其是德国经济——或许会陷入衰退的警告，将之前的学术讨论变成了一大政治议题。
德国已超越中国成为全球第一大贸易顺差国。呼吁德国加大基础设施投资以重振其放缓的经济的声音颇为响亮。不过，在紧闭的大门背后，有更大的推动力要求尽快行动：欧洲央行应买入意大利、西班牙和希腊的国债，而且是大量买入。
尽管ECB提交了一份计划，准备购买证券化的企业债券，但许多人现在认为，此类证券当前的规模不足以让这一计划起到作用。
在鹰派央行行长延斯·魏德曼(Jens Weidmann)的带领下，德国一直对ECB大量买入成员国国债的任何举措予以抵制。
一名无权公开置评的ECB高级官员称，在该行的管理委员会上，德国面临着放松其反对立场的越来越大的压力，尤其是在有关经济增长与通货膨胀的担忧正在加深的情况下。
“我想这件事一年内会实现，”此人表示。
当然，这样的举措将导致全球买家更为疯狂地购入欧元区国家的国债。而且，本周早些时候，IMF总裁克里斯蒂娜·拉加德(Christine Lagarde)警告，此类工具的强劲表现没有得到这些国家经济面的支持。
实际上，尽管债市投资者在猛踩油门，但受困于严苛监管要求的银行，仍然在踩刹车。
“每六个月就得来一次压力测试，我怎么可能去放贷？”欧洲一家大型银行的董事长说。由于不希望惹恼自己的新监管机构ECB，他要求不具名。
上周，IMF表示，该机构监测的欧洲大型银行中，70%无法通过放贷来支撑经济复苏。
“我们看到的是，金融市场中的很多业务承载着巨大风险，而实体经济在承担风险的事情上打着瞌睡，”国际清算银行(Bank for International Settlements)的高级经济师克劳迪奥·博里奥(Claudio Borio)说。这家银行是全球央行的结算行。
德拉吉在新闻发布会上表示，他并未看到欧元区存在国债泡沫的迹象，不过他明确指出，需要密切关注这一问题。
尤其是，银行业高层和债务专家指出，由于美联储(Federal Reserve)的债券购买计划，新兴市场上累积了巨额的企业与私营部门债务。
“整体债务规模持续飙升——在过去六年里，中国的债务增加了15万亿美元（约合92万亿元人民币），”咨询公司麦肯锡(McKinsey)的分析师苏珊·伦德(Susan Lund)说。“这是个很大的数字。”
在上周发布的《全球金融稳定报告》中，IMF指出，资产管理公司增加了从新兴市场上买入债券的规模，由2000年初的2650亿美元增至目前的近2万亿美元。
过去几年间，这种累积的步伐不断加快，而监管部门担心，当美国加息的时候，投资者将纷纷抽离资金，尤其是散户投资者。
专家认为，到了那个时候，各大基金将难以将这些证券脱手，因为它们不大能吸引大量的买家和卖家。
“我们的确担心，如果其中的大笔资金要同时退出，就会出现减价大甩卖，”英格兰银行(Bank of England)负责金融稳定的副行长乔恩·坎利夫(Jon Cunliffe)说。
不过，在一些观察人士看来，关于资产泡沫及各国央行应如何加以应对的讨论，其实是不得要领。他们宣称，美联储加息的话——由于美国经济正在全面复苏，可以这样设想——将是一个积极的信号，不仅对美国如此，对全球金融市场总体而言也如此。
“2015年将会加息——为什么市场要剧烈波动？”摩根士丹利(Morgan Stanley)首席执行官詹姆斯·P·戈尔曼(James P. Gorman)在周五的午餐会上反问。“之所以会加息，是因为美国经济正在好转——这是件好事。”(中国进出口网）
WASHINGTON — As global leaders sounded the alarm about a slowing world economy, a more immediate concern drew the attention of policy makers at the International Monetary Fund’s semiannual meetings last week: inflated asset prices and increasing levels of debt overseas.
Bond markets in the eurozone are booming, debt in China is at historic highs and the United States stock market, even with its sharp fall last week, has been on a tear.
As economists and politicians heap pressure on global central banks to continue, and even escalate, their unusually loose monetary policies in order to spur global demand, the fear that these measures could provoke another market convulsion is spreading.
“A major lesson of the last crisis is that accommodative monetary policy contributed to financial excesses,” said Lucas Papademos, a former vice president of the European Central Bank. “We are pursuing a similar policy for good reason. But there are limits — if you do this for too long, risks in the financial markets will materialize.”
Over the last week this debate has been playing out here: on panels at think tanks, in huddles inside and outside the hulking I.M.F. building and in formal talks between government officials and central bankers.
Mario Draghi, the president of the E.C.B., echoed these concerns on Saturday when he said that beyond concerns about the global economy, one of the main topics of discussion was “increasing financial risk-taking” by investors, especially nonbank institutions.
To a degree, the fund’s warning that the eurozone’s economy, and Germany’s in particular, might face a recession turned what had been an academic discussion into a major political issue.
The outcry for Germany, which has surpassed China as the country with the largest trade surplus in the world, to spend more on infrastructure to revitalize its flagging economy was loud enough. But behind closed doors there was an even harder push for more immediate action: a purchase by the European Central Bank of Italian, Spanish and Greek government bonds, in large quantities.
While the bank has presented a plan to purchase securitized corporate bonds, many now think that not enough of these securities exist for the plan to make a difference.
Germany, led by its hawkish central bank head, Jens Weidmann, has resisted all moves by the E.C.B. to buy government bonds in bulk.
One senior E.C.B. official, who was not authorized to speak publicly, said that within the body’s governing council, Germany is facing increased pressure to relax its opposition to such measures, especially as worries about growth and deflation increase.
“I think you will see this happen in less than a year,” the person said.
Such a step, of course, would create even more of a global buying frenzy for eurozone government bonds, and earlier in the week Christine Lagarde, the chief of the I.M.F., warned that the strong performance of these instruments was not supported by the underlying economies in their countries.
In effect, bond market investors are slamming down on the gas pedal while banks, burdened by persistent regulatory demands, still have their foot on the brake.
“How am I supposed to lend any money if I have to go through a stress test every six months?” said the chairman of a large European bank who spoke on the condition of anonymity because he did not want to offend his new regulator, the E.C.B.
Last week, the I.M.F. said that in Europe, 70 percent of the large banks it monitored were not in a position to support an economic recovery via increased lending.
“What we see is extraordinary risk-taking in the financial markets while in the real economy risk-taking has taken a holiday,” said Claudio Borio, a senior economist at the Bank for International Settlements, a clearinghouse for global central banks.
Mr. Draghi, at his news conference, said he did not see signs of a government-bond bubble in the eurozone, although he did note that the matter demanded close attention.
In particular, bankers and debt experts pointed to the tremendous buildup in corporate and private-sector debt in emerging markets that has resulted from the Federal Reserve’s bond-buying program.
“Overall debt has continued to grow quite dramatically — China’s has grown by $15 trillion in the past six years,” said Susan Lund, an analyst at McKinsey, the consulting firm. “That is a very large number.”
In the financial stability report it released last week, the I.M.F. pointed out that asset management firms have increased their purchases of bonds from emerging markets to close to $2 trillion today from $265 billion in early 2000.
The pace of this buildup has increased over the last few years, and regulators worry that when interest rates in the United States rise, investors — especially on the retail side — will pull their money out.
At that point, experts believe, the funds would have a hard time selling those securities, which tend to not attract large numbers of buyers and sellers.
“We do worry that if a lot of this money heads for the exit at the same time you could see a major fire sale,” said Jon Cunliffe, deputy governor for financial stability at the Bank of England.
For some observers, though, the debate about asset bubbles and what central banks should do about them misses a crucial point. An increase in interest rates by the Fed, assuming it happened because the American economy was in full recovery mode, would be a positive sign, they say — not just for the United States but also for global financial markets in general.
“Interest rates are going to go up in 2015 — why are the markets getting all whipsawed?” said James P. Gorman, chief executive of Morgan Stanley, speaking at a luncheon conference on Friday. “Rates are going up because the U.S. economy is doing better — and that is a good thing.”
