As investors¹ fixate on the global forces whipsawing the markets, one fundamental measure of stock-market value, the price/earnings² ratio, is shrinking in size and importance. And the diminution³ might not stop for a while.

投资者关注导致市场拉锯战的全球因素的时候，衡量股市价值的一个基本指标——市盈率，其数值和重要性都在下降。而且这一下降趋势一时还不会停下来。

The P/E ratio, thrust into prominence⁴ during the 1930s by value investors Benjamin Graham and David Dodd, measures the amount of money investors are paying for a company's earnings. Typically, companies that post strong earnings growth enjoy richer stock prices and fatter P/E ratios than those that don't.

市盈率在20世纪30年代因价值投资者本杰明·格雷厄姆和戴维·多德而出名，该指标衡量投资者为公司获利支付的资金。通常来说，获利强劲的企业股价和市盈率高于获利较差的企业。

But while U.S. companies announced record profits during the second quarter, and beat forecasts by a comfortable 10% margin⁵, on average, the stock market has dropped 5% this month.

尽管美国企业公布第二季度获利创下纪录，利润率平均较预估高出10%，但本月股市下跌5%。

The stock market's average price/earnings ratio, meanwhile, is in free fall, having plunged⁶ about 35% during the past year, the largest 12-month decline since 2003. It now stands at about 14.9, compared with 23.1 last September, based on trailing 12-month earnings results. Basedon profit expectations over the next 12 months, the P/E ratio has fallen to 12.2 from about 14.5 in May.

股市平均市盈率目前快速下滑，过去一年累计跌约35%，为2003年以来12个月的最大跌幅。根据对12个月获利的追踪，目前股市平均市盈率约为14.9，去年9月时为23.1。基于对未来12个月的获利预估，市盈率已从5月时的 14.5降至12.2。

So what explains the contraction⁷? In short, economic uncertainty⁸. A steady procession of bad news, from the European financial crisis to fears of deflation in the U.S., has prompted analysts¹⁰ to cut profit forecasts for 2011.

那怎么解释这一矛盾呢?简单说，是经济的不确定性所致。从欧洲金融危机到对美国通缩的担忧，坏消息纷至沓来，令分析师纷纷调低了对2011年的获利预估。

"The market is worrying not just about a slowdown, but worse," said Tobias Levkovich, chief U.S. equity¹¹ strategist at Citigroup Global Markets in New York. "People want clarity before they make a decision with their money."

花旗环球金融驻纽约美国股市首席策略师莱乌科维奇说，市场不仅在担心经济放援，而且在担心更糟糕的事情，人们在对资金作出决定前，他们希望把情况弄明白。

Three months ago, analysts expected the companies in the Standard & Poor's 500-stock index to boost profits 18% in 2011. Now, they predict 15%. Mutual-fund, hedge-fund and other money managers put the increase at closer to 9%, according to a recent Citigroup survey, while Mr. Levkovich' s estimate is for 7% growth.

三个月前，分析师预计2011年标准普尔500指数成分股获利将增长18%，目前他们预计增长15%。根据花旗集团最近的调查，共同基金、对冲基金及其他资金管理机构认为增幅接近9%，莱乌科维奇预计增长7%。

"The sustainability of earnings is in doubt," said Howard Silverblatt, an index analyst⁹ at S&P in New York. "Estimates are still optimistic."

标准普尔驻纽约指数分析师西尔弗布拉特说，获利的持续性让人怀疑，但预估依旧乐观。

Equally troublesome，analysts' forecasts are becoming scattered¹². In May, the range between the highest and lowest analyst forecasts of s&P 500 earnings per share in 2011 was $12. Morgan Stanley predicted $85 a share, while UBS predicted $97 a share. Now, the spread is $15. Barclays said $80 a share; Deutsche Bank predicts $95.

同样让人烦恼的是，分析师的预估有多有少。5月时，分析师对2011年标准普尔500指数成分股的每股盈余进行了预估，最高和最低差值为12美元。摩根士丹利预计为每股盈余85美元，瑞银预估为97美元。目前最高和最低差值为 15美元，巴克莱预计为每股盈余80美元，德意志银行预计为95美元。

When profit forecasts are tightly clustered, it signals to investors that there is consensus¹³ among prognosticators; when they diverge¹⁴ wildly, it shows a lack of clarity. The P/E ratio tends to fall as uncertainty rises, and vice¹⁵ versa.

当获利预估差不多的时候，其向投资者暗示，分析师的预估达成了一致;当分歧较大的时候，显示市场缺乏清晰度，这时候市盈率通常因不确定性上升而下跌，反之亦然。

"A stock is worth its future earnings, but that involves uncertainty," said Jeremy Siegel, professor of finance at the University of Pennsylvania 's Wharton School. "The more uncertainty there is, the lower the P/E will be." Not only is the P/E ratio dropping, it also is in danger of losing some of its prominence as a market.

宾州大学沃顿商学院金融学教授西格尔说，一只股票与它未来的获利相匹配，但存在不确定性，如果不确定性越高，市盈率就越低。不仅是市盈率下降，就是该指标也有可能失去一些作为市场基准的声望。