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【纽约客】不靠谱的股市熔断机制 | 取经号


导读


短寿的股市熔断机制只在中国存在了短短的4天。这一金融市场上的保险丝为何在不起作用,反而加快了股市的崩溃?这其中既有股民的心理因素作怪,也有机制本身的问题。回顾历史,原来美国的熔断机制,也曾几度迷茫。下一步,中国的熔断机制将何去何从?


正文


January 12, 2016

The Dubious Logic of Stock-Market Circuit Breakers

不靠谱的股市熔断机制

By Paul Kedrosky



Stock-market circuit breakers, which trigger cooling-off periods in financial systems, are a good idea in theory, but they weren’t in the Chinese design. Credit Photograph by Imaginechina via AP


Many things that are supposed to make you safer don’t actually do so. Taking off your shoes at airports, for example, is largely security theatre. (How many prospective shoe bombers have been nabbed since Richard Reid?) But the practice offers the impression of protection, so it stays—just to be on the safe side, you know.

许多应该让你感觉到更安全的东西实际上并不能保障你的安全感。比如说,在机场脱掉鞋子进行安检很大程度上是一种“安全场”行为。(自理查德·里德案之后有多少潜在的炸弹客被抓住了?)但是这一行为给人保护的感觉,所以它保留了下来——只是为了安全起见,你懂的。


Other safety devices, like bicycle helmets, may have a more subtly undermining effect, at least according to some “risk homeostasis” theorists, who hold that helmets can lead some people, feeling more secure in the knowledge that they’re “safe,” to ride faster, increasing the potential for accidents, or to ride less often, making them less healthy. (Studies on the subject have shown mixedresults.) To take another example, people whose cars have anti-lock braking systems are sometimes said to drive less cautiously in slippery conditions.

其他的安全措施,比如自行车头盔,其被低估的影响力则可能更加微妙,至少根据一些”风险平衡”理论家的说法,他们认为头盔可以让一些人感觉到更加安全,从而骑车更快,这样反而增加了事故的潜在风险,或者减少骑车频率,这样做更不利于健康。(对这一课题的研究表明两种结果都是存在的。)再比如,据说车子装有刹车防抱死制动系统的人们有时却会在路滑时掉以轻心。


Then there is a third class of misguided safety measure. This type creates the illusion of safety but actively makes things worse. A good example is antibacterial soap, which has been shown to be no more effective than regular soap, and which carries risks like the creation of antibiotic-resistant bacteria. Circuit breakers in financial markets, which are intended to automatically shut down trading when the market declines by a predetermined amount, arguably belong to that third group. This was evident last week in China, where new circuit breakers, put in place to prevent market crashes like the ones the country experienced last summer, were suspended on January 7th, only four days after being implemented.

此外还有第三类误导性的安全措施。这种类型的措施造成安全的幻觉,但其实会令情况变得更糟。一个很好的例子是抗菌皂,实践已证明抗菌皂不比普通的香皂更能有效杀菌,并且抗菌皂可能会产生耐药菌。金融市场的熔断机制本意是当股票指数跌到熔断阀值时自动中止交易,这个机制应该说属于第三类安全措施。这在上周的中国体现的尤为明显,新的股票熔断机制问市,本意是以预防股市像去年夏天经历过的那样崩盘,但熔断机制仅仅在实施四天后就于1月7日被终止。


The Chinese circuit breakers were designed to kick in progressively, at two levels of decline. The first threshold was a market drop of five per cent, which would cause an automatic fifteen-minute pause in trading. The second one, which would shut down trading for the day, kicked in after a seven-per-cent decline. But in practice, rather than protecting investors, the controls appear to have made the markets more crash prone, causing wholesale trading shutdowns last Monday and Thursday. On Thursday, trading stopped after only twenty-nine minutes.

中国的熔断机制原意是在股市设置两个跌幅熔断点,以起到积极作用。第一个阈值是指数下跌5%,将暂停交易15分钟,而第二个阀值为7%,当指数触发7%阀值时则暂停当天交易。但实际上,这一调控令股市更加易于崩盘,而非对投资者起到保护作用。造成了上周一周二股市的全面关停。上周四,交易在开市仅仅29分钟后就停止。

The appeal of circuit breakers in financial markets is obvious: when market behavior starts to present a major risk, the breaker trips, much like a real-world fuse would, imposing a cooling-off period before anything (a toaster, an economy) gets fried. They’re a good idea, at least in theory, but they weren’t in the Chinese design.

金融市场熔断机制的尝试诉求是明确的:当市场行为开始显露出面临重要风险时,熔断起效,它的作用很像保险丝,在任何东西(一个面包机或者经济)变得过热前(自动)“跳闸”,加入一段冷静期。这是一个好主意,至少在理论上来说是这样,但这一机制不适用于中国。


To understand why circuit breakers can make markets less “safe,” imagine that you’re a Chinese trader on a day when markets are approaching a five-per-cent decline. What do you do? Most likely, you sell madly, trying to get your orders in before the fuse is triggered and the markets are halted for fifteen minutes. In effect, you help cause what you are trying to avoid. Then, when the exchanges open again, what’s your single biggest fear? That markets will decline another two per cent, causing trading to end for the day. So what do you do now? As soon as the market reopens, you sell frantically, as do your peers, causing the seven-per-cent fuse to be tripped even faster. And once that has happened for the first time it’s likely to happen again. Investors will remember previous shutdowns, so if they’re leaning toward selling on a given day they’ll try to do so even faster this time, to avoid being caught out. That’s what happened in China on Thursday.

要想理解熔断机制为何会使股市安全性降低,想象一下你是一个中国股民,在沪指逐渐下跌逼近5%阀值的某天进行交易。你会怎么做?最可能的是,你会疯狂地抛售,试图赶在熔断点触发,市场暂停15分钟之前完成交易。实际上,你的行为助长了你试图避免的情况。然后,当股市恢复交易,你最大的恐惧是什么?是指数会再度下跌两个百分点,造成当天的交易终止。那么这时候你会做什么呢?等股市一恢复运行,你就像其他股民一样,疯狂地卖出股票,这样一来却使得7%的熔断阀值到来的更快。股民会记住先前的闭市,因此如果他们倾向于在特定的一天卖出股票,(下一次)这样的时候他们会试着卖的更快,以免被套牢。这就是上周四在中国股市发生的事情。


This sort of mess is more likely to happen when breaker systems are poorly designed. Lousy breakers have their thresholds set too low, guaranteeing that they’re tripped constantly, or are set too close together, creating a kind of attraction effect that pulls investors from one break point to the next, like iron filings to a nearby magnet. Chinese regulators managed to make both mistakes. They set the levels too low—five-per-cent declines are much more common in China than they are here—and made the breakpoints too close together. The end result was that, in trying to make safer a system they didn’t trust, regulators likely helped make it more volatile.

当熔断机制设计不合理时,这样一团糟的局面很有可能会发生。熔断的阀值设置得太低,使得它们连续跳闸,并且两个阀值距离太接近,造成了一种磁吸效应,将投资者(快速)从一个熔断点拉到另一个熔断点,就像硬币被近旁的磁铁所吸附。中国的调控者们同时犯下了这两个错误。他们将阀值设的太低——5%的跌幅在中国比在美国更为常见——并且他们的(一级二级)熔断点过于接近。这样导致的结果就是,调控者们本来试图让他们不信任的股市更加安全,但却使得其更加不稳定。


By way of comparison, in the U.S, the S&P 500 breakers have three thresholds: at seven per cent, thirteen per cent, and a total shutdown in the event of a whopping twenty-per-cent decline. But although higher triggers and wider fuses are better they don’t solve all the structural problems with market circuit breakers, as the U.S. has discovered.

比较来看,在美国,标普500指数有三个熔断阀值:7%,13%,以及跌幅达到20%的巨量时关闭股市。但是尽管较高的触发点和更广的熔断范围更好,但美国的实践发现,熔断机制不能解决所有结构性问题。


Our flirtation with financial-market circuit breakers is relatively recent, not to mention conflicted and entertainingly fickle. Following the crash of October, 1987, there were immediate calls to create a way of stopping market free falls. But, despite the potential economic consequences of such collapses, many people still objected to the idea of a fail-safe device, on both the technical grounds outlined above and on the principle that the markets should be allowed to find their own levels, falling as far it took to find new buyers. (This argument echoed Treasury Secretary Andrew Mellon’s infamous call to Herbert Hoover, during the Depression era, to let stocks fall and “purge the rottenness” from the system.)

我们在近代才引入金融市场熔断机制,考虑并不成熟,更不要说了解市场冲突性戏剧性的变化了。在1987年10月的美国股灾后,立即出现了要求寻找方法阻止股市的自由落体的呼声。但是,尽管这样的股市崩盘潜藏(严重的)经济后果,许多人依然反对采用故障安全装置的想法,他们认为,(股市的故障安全装置)技术上来说不可行,并坚持原则称市场应该自我发现它的基准,在找到新买家前放任其下跌。(这一说法与经济大萧条时期美国财政部长安得烈-梅隆对赫伯特胡佛臭名昭著的建议遥相呼应,梅隆号召,“让股票下跌,并从系统内“清除腐败”)。


Nevertheless, market-wide U.S. circuit breakers were instituted in 1988. After producing increasingly frequent trading pauses over the next decade, as the size of the market grew, the breakers went mad in 1997, triggering constantly and causing a full shutdown on October 27th. This caused a bout of recriminations and some significant tweaks to the system, notably a shift to percentage-based thresholds. Since 1997, market-wide breakers have been triggered precisely … never. No market event since 1998—including the worst declines of the Great Recession and the “flash crash” of May, 2010, when the value of many major stocks briefly plummeted in value—has triggered a system-wide stoppage. (Stock-specific breakers, which were implemented in the U.S. after the flash crash, are routinely triggered; these don’t exist in China.)

尽管如此,美国股市的熔断机制(终于)在1988年创立。随着股市规模的增长,接下来的十年里,熔断机智造成了越来越频繁的交易停顿,随着股市规模的增长,熔断机制在1997年失控了,在10月27号股市持续跳闸并造成了全面闭市。这造成了(证监会)决策者们的相互指责,并对熔断机制做出了一些重要调整,特别是对熔断阀值百分比设定的改变。1997年以来,整个大盘范围的熔断机制从未被十分精准地触发。1998年后股市没有什么大事发生——包括经济萧条时期最严重的衰退和2010年5月的美股闪崩在内。美股闪崩时许多主要股票的市值大幅缩水,触发了全系统的交易暂停。(美股闪崩后开始实施专业的股票熔断机制,此机制会被周期性触发;这些在中国并不存在)。


In the wake of last week’s market swings, U.S. regulators and market observers were quick to chide the poor design of China’s circuit breakers. (“I don’t trust anything about China,” CNBC’s Jim Cramer said. “They had no clue, it seems, of what the circuit breakers would do in terms of the consciousness of the country.”) But Americans shouldn’t be too quick to judge: both countries have been kidding themselves about the extent to which their circuit breakers accomplish the goal of making the markets safer. It’s true that China, which is newer to capital markets and more anxious about their volatility, made things worse by imposing harsh controls. But while the U.S. approach has become more sophisticated, over time, it has been left with an ugly mix of complex single-stock curbs and market-wide breakers that are effectively security theatre.

在上周股市波动之后,美国的监控者和市场观察者迅速指责了中国熔断机制的不合理设计。(“我不相信中国的任何东西。”CNBC的杰米克莱姆说道。“看起来中国没有意识到熔断机制会起什么作用。”但是美国人不该评判太快:关于熔断机制能在多大程度上实现让股市更安全的目标,中美两国都曾犯过错误。中国是资本市场的新人,对股市的波动性更加焦虑,其强硬的管控反而使情况更糟。但美国的方案随着时间推移已变得更加成熟,已经形成了复杂的单股限制措施和全股市性的熔断机制的组合,这是股市有效的“安全场”。


For now China’s breakers are gone, and its markets are again trading freely; Monday saw a five-per-cent dip in the Shanghai index and a six-and-a-half-per-cent drop in the Shenzhen. But don’t bet that the breakers will be gone forever. Once things settle down, and Chinese regulators have a chance to reflect on what went wrong, we will likely see their return. It’s possible that China will find the right balance for its volatile markets, but it’s possible, too, that it will follow the U.S.’s example, setting the breakers where they’ll never be triggered at all—left in place just to be on the safe side, you know.

如今中国的熔断机制已经消失了,股市恢复了贸易自由,周一沪指突降5%,深指下降6.5%。但是不要断言熔断机制会永远消失。一旦尘埃落定,中国的管控者们有机会反思是哪里出了差错,我们可能会看到熔断机制卷土重来。中国可能会为其波动性的股市找到正确的平衡,但也有可能,中国会步美国的后尘,制定永远不会被触发的熔断值——仅仅为了安全起见,你懂的。


外媒简介




《纽约客》(The New Yorker),也译作《纽约人》,是一份美国知识、文艺类的综合杂志,内容覆盖新闻报道、文艺评论、散文、漫画、诗歌、小说,以及纽约文化生活动向等。《纽约客》现由康得纳斯出版公司出版。《纽约客》不是完全的新闻杂志,然而它对美国和国际政治、社会重大事件的深度报道是其特色之一。他一方面保持了轻松幽默的主题风格,另一方面它也很快成为严肃新闻报道和文学创作的一处显要出版窗口。


学习笔记


1. Security theatre:安全场。

Security theater is the practice of investing in countermeasures intended to provide the feeling of improved security while doing little or nothing to actually achieve it. Some experts such as Edward Felten have described the airport security repercussions due to the September 11, 2001 attacks using commercial jetliners in the United States, as security theater.

在对策中投资,以营造出安保加强的错觉,但实际效果寥寥。911事件中使用了商业飞机,机场其后在安保上采取的措施被爱德华·费尔顿(Edward Felten)等专家称之为“安全场”。


2. Homeostasis:平衡

N. the maintenance of metabolic equilibrium within an animal by a tendency to compensate for disrupting changes (动物间的)动态平衡


3. Prone

(1)Adj. To be prone to something, usually something bad, means to have a tendency to be affected by it or to do it. 易于 (受某事物影响或做某事) 的

例:

For all her experience as a television reporter, she was still prone to camera nerves.

尽管有丰富的做电视记者的经验,她仍然倾向于在镜头前紧张。

(2)COMB in Adj -prone combines with nouns to make adjectives that describe people who are frequently affected by something bad. 易受…影响的 (与名词结合构成形容词)

例:

…the most injury-prone rider on the circuit.

…赛车道上最容易受伤的车手。

本文取后种用法


4. Lousy:糟糕的

(1)Adj. If you describe something as lousy, you mean that it is of very bad quality or that you do not like it. 糟糕的

例:

He blamed Fiona for a lousy weekend.

他指责菲奥娜让他过了一个糟糕的周末。

At Billy's Café, the menu is limited and the food is lousy.

比利餐馆饭菜品种有限,质量也很糟。

(2)Adj. If you describe someone as lousy, you mean that they are very bad at something they do. 蹩脚的

例:

I was a lousy secretary.

我曾是个蹩脚的秘书。

(3)Adj. If you describe the number or amount of something as lousy, you mean it is smaller than you think it should be. 微薄的

例:

The pay is lousy.

薪水少得可怜。

(5)Adj. If you feel lousy, you feel very ill. 极不舒服的

例:

I wasn't actually sick but I felt lousy.

我其实没有生病,但感觉很不舒服。

本文取第一种用法。


5. Fail-safe:故障安全的

Adj. Something that is fail-safe is designed or made in such a way that nothing dangerous can happen if a part of it goes wrong. 有故障保险功能的; 有自动防障功能的

例:

The camera has a built-in failsafe device which prevents it from working if the right signals aren't received.

这部照相机内部有故障保险装置,可以令照相机在未接收到正确信号时无法运行。


6. Flash crash:美股闪崩

The May 6, 2010, Flash Crash also known as The Crash of 2:45, the 2010 Flash Crash or simply the Flash Crash, was a United States trillion-dollar stock market crash, which started at 2:32 and lasted for approximately 36 minutes.:1 Stock indexes, such as the S&P 500, Dow Jones Industrial Average and Nasdaq Composite, collapsed and rebounded very rapidly. The Dow Jones Industrial Average had its biggest intraday point drop (from the opening) up to that point, plunging 998.5 points (about 9%), most within minutes, only to recover a large part of the loss.

2000年5月6日上演的Flash Crash。美国道琼斯指数不到半小时的时间暴跌700点,之后又戏剧性的反弹600点。美国股市暂时性的蒸发了1万亿美元,创造了道琼斯指数单日日内下跌的最高纪录。


翻译:田阳

校对:毛燏

笔记:杨雪

策划:胡雅琳




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