An overdue sell-off flusters exchanges and sobers investors

　　迟来的抛售搅乱了股市，也惊醒了投资者

　　IT WAS almost inevitable something bad would happen. Barely a ripple had disturbed the smooth surface of financial markets since May last year. But on February 27th share prices were suddenly hit by a wave of selling.

　　是福不是祸，是祸躲不过。自从去年5月以来，金融市场静如止水，鲜有波动。然而在2月27日，一股抛售浪潮导致股票价格一泻千里。

　　It is always possible to find plausible reasons for a sudden stockmarket fall after the event—less easy to pick them beforehand. The immediate catalyst for this week's troubles appeared to be a near-9% fall in the Chinese stockmarket, itself triggered by stories that the authorities were about to clamp down on speculation. But the truth is that investors were simply looking for excuses to take profits.

　　人们总能为股市的突然下跌找到合理的解释，然而做事后诸葛容易，做到晓之于未然难度就大多了。政府准备打击投机活动的传言引发中国股市暴跌近9%，这似乎是本周市场动荡的直接诱因。然而真相是，这只是投资者为收割利润寻找的借口。

　　A decline looked overdue. Wall Street had enjoyed its longest period without a 2% daily fall for more than five decades. Margin debt—the money sharebuyers borrow from brokers—had just passed its previous peak, recorded during the dotcom bubble. Risky assets, from high-yield corporate bonds to emerging-market debt, were offering historically low yields.

　　其实这样的下跌早就该发生了。美国股指日跌幅小于2%已维持了50多年，超过史上任何一段时期。保证金负债量(margin debt，股票买家向经纪人借入的资金)超过了此前互联网泡沫时创下的纪录。高收益公司债券和新兴市场债务等风险资产提供的收益也创下历史新低。

　　When it came, the sell-off was dramatic. At around 3pm New York time on February 27th, the Dow Jones Industrial Average was down by a couple of hundred points. In less than a minute, it plummeted another 200 points—a rate of decline that traders said was unprecedented.

　　股票抛售一来便来得如此猛烈。2月27日下午3点左右，道琼斯工业平均指数已下跌几百点，然后在不到一分钟的时间内，道指直泻200点；速率之快，史无前例。

　　The speed of the fall was caused by a tabulation delay. The data-systems arm of Dow Jones, which calculates the average, had been unable to process orders quickly enough as they surged during the afternoon. At 3pm the firm switched to a back-up system in an effort to unblock the pipe. This did the trick, but caused a massive instantaneous fall in the average as it readjusted after the delay.

　　下跌如此之快起因于“计算延迟(tabulation delay)”。由于计算平均指数的数据系统来不及处理当天下午大量涌入的订单，为畅通道路，道琼斯公司与3点启用了备用系统。新系统起了作用，却引发重新调整后的道指瞬间大幅下挫。

　　This was not the only problem. Floor traders were unable to keep track of computer-driven orders, particularly those selling exchange-traded funds—baskets of stocks linked to an index. At its low, the Dow was down 546 points, among the worst points falls in its history.

　　问题不止这一个。场内交易商(floor traders，指在交易所场内主要为自己或自己占有份额的帐户进行交易的交易所成员—译注)无法追踪电脑驱动的订单，特别是卖出上市交易基金(ETF，盯住某一指数的股票组合)的订单。当日道指最大跌幅达546点，成为史上最大单日跌幅之一。

　　None of this was good news for John Thain, the NYSE's chief executive. He was seen on the trading floor just after the 3pm meltdown, looking flustered and spurning interview requests. With competition between traditional exchanges and electronic networks hotter than ever, the last thing he needs is questions over the robustness of the NYSE's technology.

　　对纽约证交所的首席执行官约翰·塞恩(John Thain)来说，没有一条是利好消息。下午三点的大崩盘后不久，他便出现在交易大厅里，看上去惊慌失措的他拒绝任何采访。在传统的交易所和电子网络之间的竞争愈发激烈的时候，他最不希望听到的就是有关纽约证交所是否还具有活力的质疑声。

　　Inevitably, Wall Street set the tone for the rest of the world, with European, Asian and emerging markets falling heavily in its wake. But on February 28th the American market showed signs of stabilising.

　　华尔街为世界其它地方的股市定下了基调：欧洲、亚洲和新兴市场的股市不可避免地紧跟着大幅下跌。但在2月28日，美国股市出现回稳迹象。

　　Will that be it? Certainly those investors interested in the “fundamentals” can find things to worry about. Tensions over Iran's nuclear programme are still high, and the oil price is $10 a barrel above its recent lows. The recent defaults in the subprime mortgage market may be affecting other bond investors and cutting off credit to the housing market. Some recent American economic data have been weak and Alan Greenspan, the former chairman of the Federal Reserve, has mused publicly about the possibility of a recession.

　　但果真如此吗? 注重观察“经济基本面”的投资者当然有担心的理由： 伊朗核计划引发的紧张局势不见缓和；每桶石油的价格比近期最低价高出10美元。最近次优房贷市场上的违约现象不仅可能会给其他债券的投资者带来不利影响，还会切断房市的信贷来源。最近的数据显示美国经济走弱，美联储前主席艾伦·格林斯潘也在公开探讨美国经济衰退的可能性。

　　His successor, Ben Bernanke, did best to allay fears of an immoderate slowdown. If he is wrong, he can always start lowering interest rates. The "flight to safety"has already caused Treasury bond yields to fall, cutting the borrowing costs of homebuyers.

　　而他的继任者本·伯南克则竭尽全力缓和经济衰退的预期所带来的紧张气氛。如果他出了错，他总还有个杀手锏——降息。资金向安全资产转移的现象(flight to safety)使得国债收益率下跌，降低了购房者的借款成本。

　　But it may be the internal dynamics of the markets, not the evolution of the wider economy, that decides whether this is a brief shakeout or the start of a serious correction. Periods of low volatility tend to encourage risk-taking. Hedge funds have a natural inclination to buy higher-yielding (and thus riskier) instruments and sell low-yielding assets, since this delivers a positive income or “carry”. When the market falters, these positions rapidly lose money. For example, the modest rise in the yen—2.3% against the dollar on February 27th—wiped out about half the annual interest gain accruing to investors who sold yen and bought dollars. Those who gambled on the “carry trade” may decide to cut their losses.

　　然而，这次暴跌究竟是一时的动荡，还是市场大幅调整的开端，取决于市场内部的变动，而非整个经济体的发展。波动率较低的时期风险交易旺盛。对冲基金天生倾向于卖出低收益的资产，购进高风险高收益的金融工具，以此取得正收益或者“套利”。当市场出现动荡，这些头寸将迅速贬值。比如2月27日日元对美元小幅升值了2.3%，卖出日元买进美元的投资者积累下来的年利息所得瞬间被抵消了一半。这样，这些“套息交易”的玩家们可能会决定拆仓止损。

　　As they do so, other investors may hurry to shift their feet. Investment banks use “value-at-risk” models which mean that, when volatility rises, they cut the capital they allocate to trading. This usually means selling assets. So a sudden jump in volatility tends to generate further volatility. "The sell-off was merely a warning shot," says Chris Watling of Longview Economics, a strategist who recently forecast a correction. “"nvestors should expect further selling in coming weeks."

　　如果它们果真如此，其他投资者也会迅速转移资金。投行广泛采用“风险价值”模型：当市场波动率上升时，它们将减少交易资金，而这通常意味着减持资产。由此，波动率的突然上升将会导致市场上更大的波动。长景经济顾问公司(Longview Economics)的策划师克里斯·沃特林(Chris Watling)最近预测将有一次市场调整：“这次抛售还只是个警告，未来几周这还将愈演愈烈。”

　　What matters is how many actors have all made the same bet. One of the oldest market mistakes is the assumption that you can get out of a position as easily as you entered into it. According to Goldman Sachs, the latest jump in the Vix (a measure of stockmarket volatility) took it eight standard deviations from its average. If conventional models are correct, such an event should not have happened in the history of the known universe. Then again, the move in energy prices that caused the collapse last year of Amaranth, the hedge fund, was a nine standard-deviation event. Perhaps modellers do not know the universe as well as they would like to think.

　　关键是参与者中有多少进行了这般相同的赌博。好进就好出的想法是金融市场上最老套的错误之一。高盛的报告显示，波动率指数(Vix，衡量股市波动性大小的指数)最近上升了800点。如果常规的模型无误的话，这在已知世界的历史中本不该发生。其实历史早在去年就上演过一次，能源价格的变动导致了对冲基金Amaranth的破产，当时Vix的涨幅达到了900点。

　　This is what makes markets prone to nasty surprises and it explains why investing with borrowed money can be dangerous. If some bank or big hedge fund has been caught out by the sudden sell-off, the events of February 27th could have lasting implications. The stockmarket has seen blacker Tuesdays. But this one may cast a long shadow.

　　这是市场易受突发不利事件影响的原因，也解释了为什么借钱投资是危险的。如果一些银行和大的对冲基金被这次突然抛售逮个正着，这次“2·27事件”的影响将会更加持久。尽管股市的历史上不乏更加黑暗的“星期二”，但这一次投下了道长长的阴影。