There are two immediate reasons to worry. 担心有两方面的直接原因。

First, markets have been steadily rising against a backdrop of extraordinarily loose monetary policy. 首先，市场一直是在一种额外宽松的货币政策背景下稳步上涨的。

Central banks have kept short-term interest rates close to zero since the financial crisis of 2007-08  自2007-08年金融危机以来，各家央行把短期利率维持在接近于0的水平，

and have helped depress long-term rates by purchasing $11trn-worth of government bonds through quantitative easing. 并且借着通过量化宽松购买价值1.1万亿美元的政府债券之机，帮助打压了长期利率。

Only now are they starting to unwind these policies. 只是在目前，它们才开始放松这些政策。

The Federal Reserve has raised rates twice this year and will soon start to sell its bondholdings. 美联储今年已经升息两次，而且不久还将卖出其债券持有。

Other central banks will eventually follow. 其他央行终将步其后尘。

If today's asset prices have been propped up by central-bank largesse, its end could prompt a big correction. 如果目前的资产价格是被央行的慷慨大方所推高的，它的终结可能促成一次大调整。

Second, signs are appearing that fund managers, desperate for higher yields, are becoming increasingly incautious. 其次，渴望更高收益的基金经理们正在变得愈发不谨慎的迹象正在显现。

Consider, for instance, investors' recent willingness to buy Eurobonds issued by Iraq, Ukraine and Egypt at yields of around 7%. 例如，考虑一下投资者最近购买由伊拉克、乌克兰和埃及以7%左右的收益率发行的欧元债券的意愿吧。

But look carefully at the broader picture, and there is some logic to the ongoing rise in asset prices. 但是，细观大局，资产价格的这种持续上涨是有逻辑的。

In part it is a response to an improving world economy. 它部分是对正在改善的世界经济的一种反映。

In the second quarter of this year global GDP grew at its fastest pace since 2010,  在今年第二季度，全球GDP以2010年以来的最快步伐增长了，

as a recovery in emerging markets added impetus to longer-standing upswings in Europe and America. 这是因为新兴市场的复苏给欧洲和美国的更持久的上涨添加了动力。

As our special report this week argues, emerging-market economies have come out of testing times in far more resilient shape. 正如我们本周专题报道所言，各个新兴市场经济体已经以极具弹性的姿态走出了考验时期。