When children put their hands in the fire, they learn from the painful experience not to repeat that dangerous action. This, at least, was the sensible notion of philosopher David Hume.
Investors appear slower-witted than Hume’s toddlers. After speculative booms, euphoria commonly returns, only to be followed by a second collapse. China’s overheating stock and property markets provide a prime example of this “echo bubble” phenomenon.
在2007年10月达到顶峰前两年，上海综合指数上涨了四倍。随后，市场揭示了其价值的三分之二以上。然而，到八月初，中国股票从他们的低谷价值翻了一番。
市场泡沫通常伴随着快速的信贷增长。在今年上半年，中国银行借了超过1万亿美元，相当于该国GDP的大约四分之一。北京高级政策制定者承认，这一贷款大部分都陷入了物业和股票市场。
Turnover in stocks has returned to bubble-era levels. On July 28 the value of A-shares traded in China — $63 billion — exceeded for the first time the combined turnover of the London, New York and Tokyo stock exchanges. Daily volume on the Hong Kong Stock Exchange, where many Chinese companies are listed, has doubled from its March low and has been running at about four times the average levels of the past decade.
许多中国公司在上海和香港有双重上市。这些股票具有相同的经济价值。理论上，他们应该以相同的价格交易。事实上，上海上市的保费列出了股票提供了市场情绪的迹象。自去年的低迷以来，A股溢价翻了一番，并且在2007年最近见过的200％的水平低于200％。
Initial public offerings are also back in fashion. The July flotation of Sichuan Expressway Co. was more than 400 times oversubscribed. Shares in the toll road operator climbed threefold on the first day of trading. One analyst calculated that at its height the company was valued at $290 per square meter of asphalt. Valuations for the overall market have also returned to heady levels: The Shanghai composite recently reached 33 times normalized earnings.
新进入者的到来是另一个市场欣快感的晴雨表。到7月底，每周在中国打开了近一百万个新的经纪账户。
企业内部人似乎了解这场比赛的领导。公司正在旋转子公司，以利用夸大估值。业内人士的股票销售也攀升。“当鸭子嘎嘎时，喂它们”是一个古老的中国商业格言。
The real estate market is also buzzing. The authorities have instructed banks to lower lending standards on mortgages and to provide more second mortgages, which presumably are being used to finance speculative property purchases. Despite anecdotal evidence of low occupancy rates in new apartment blocks in Beijing and elsewhere, residential sales have picked up strongly. The house price index of several major cities is up 13 percent since the February low, according to John Makin of the American Enterprise Institute. A Morgan Stanley report suggests that home prices in several leading Chinese cities already exceed ten times average household incomes.
Commercial real estate developers are involved in a frenzied land grab and have been paying record sums for land in Shanghai and Beijing. The Wall Street Journal recently observed that Beijing property prices have returned to levels last seen a couple of years ago. Yet it is widely acknowledged that office space in the major cities is superabundant. Jack Rodman, a former Ernst & Young real estate executive, reckons that Beijing’s central business district has a vacancy rate of more than 4 percent. Rodman also claims that asking rates for new offices have fallen by half.
中国经济的基础恶化担心许多观察员。出口已暴跌。经济增长是由不断增长的投资水平的推动，尽管有严重的工业产能过剩。国有企业急于建立令人怀疑的经济可行性的基础设施项目。
然而，华尔街再次播放大傻瓜游戏，经常悄然承认狂热的狂热，但无法抵抗快速利润的诱惑。“音乐何时停下来？”一位经纪战略师最近询问了中国股市在建议客户之前，“不要太早离开聚会。”我们之前没有听过那个地方吗？
什么解释了回声泡沫？行为金融专家詹姆斯蒙蒂尔争辩说，投资者遭受“保守主义偏见”。在泡沫突发后，投资者的期望保持在泡沫阶段。它们用于过度估值和轻松的利润。
Nobel economics laureate Vernon Smith has demonstrated in classroom experiments how momentum traders can push share prices away from fair value. Smith found that one crash was not sufficient to change behavior. Traders become prudent only after a second market collapse. The motto of the broken speculator might read: “Twice bitten, thrice shy.”
回声泡沫还有其他可能的解释。由于中国的案例，萧条后，利率一般普遍降低。道德风险也起着重要作用。当局采取行动抵消投机性萧庞的令人不愉快的后果，而是通过减少鲁莽行为的痛苦，他们鼓励重复。
今天许多投资者押注于北京continue driving the economy forward while preventing future market declines. Yet a similar belief in the power of governments to support inflated asset markets has accompanied many frenzies, starting with the South Sea Bubble of 1720.
对12项此类事件的调查 - 从1830年代英国铁路狂热到2005年的沙特蝌蚪泡沫 - 表明回声泡有共同的特征。典型的一个比熊市的持续时间长，但不仅仅像前面的泡沫一样。平均而言，回声泡沫爬到距离到峰值的十个月。此外，回声的尺寸与早期臂的尺寸相成比例，其平均大约三分之一的尺寸。
那么中国回声泡沫如何测量？嗯，上海复合材料的峰谷下降为67％;正在考虑的十几个气泡也落后了三分之二。自槽以来，中国股票加倍，从而超过了平均回声泡至大约10个百分点。中国回声泡沫大约是前一个繁荣的三分之一，这符合历史比。
The greater fools of Wall Street who argue that the Chinese market will continue rising for months to come might consider the following: Echo bubbles normally fade when valuations have climbed to about one standard deviation above the mean. This is roughly the level that Chinese stocks reached earlier this summer. The Shanghai market had been rising for ten months by August. By coincidence, this is also the average length of the dozen former echo bubbles.
Edward Chancellor是Devil的作者，以GMO的资产分配团队的Hindmest和高级成员带走。