BBC雙語 | 成也蕭何，敗也蕭何——機器人演算法引發美股暴跌

02-17

昨天，美股大幅下挫，道指一度暴跌近1600點，創歷史最大單日下跌數字。據市場數據統計，美股單日蒸發逾1萬億美元市值，美股市值跌至大約29萬億美元。

究竟是什麼導致了如此大幅的下跌？

BBC的這篇文章給出了一種解讀，那就是我們如今繞不開的AI世界。AI在我們的生活中已經無處不在、無孔不入，你可能閱讀的某一篇新聞就是AI寫的，你聯繫某位客服的回答就是一個AI機器人，而現在，這些AI在金融交易中也已經大行其道。因為它具備了人類不具有的一個品質：秒速出擊。這種瞬間作出的交易反應當然有利有弊，可能比他人更快地抓住機會，也可能誤讀了某些信息，今天就來看看BBC的這篇新聞。（譯文為筆者所配）

Tips—與下跌相關的辭彙：

英文：

fall
market plunge
market tumble
(index) crash (800 points)
The explosive speed of the fall
went into freefall
steep market falls

中文：

下跌
暴跌
跳水
重挫

Did robot algorithms trigger market plunge?

機器人演算法引發了市場暴跌?

6 February 2018

The speed of Mondays fall was accelerated by algorithms

演算法加劇了周一下跌的速度。

Robot trading has accelerated this weeks market dive and may have sparked the sell-off, experts say.

專家表示，機器人交易加速了本周的市場跳水，並可能引發了拋售。

Financial firms use computers programmed with complex sets of instructions known as algorithms.

金融公司通常會使用計算機程序進行交易，它們也被稱為演算法，包含一堆複雜的指令。

They identify trading opportunities and then strike faster than any human could.

當演算法發現交易機會，會比任何人類以更快的速度進行出擊。

Algorithmic trading has become so ubiquitous that some estimate well over half of all trading of the S&P 500 Index is done this way.

如今，演算法交易已經變得非常普遍，有人估計，超過一半的標準普爾500指數的交易都以這種方式在進行。

Such automated trading almost certainly accelerated the sell-off on Monday, which saw the Dow Jones Industrial Average crashing 800 points in ten minutes.

這種自動交易幾乎肯定加速了周一的拋售，道瓊斯工業平均指數在10分鐘內暴跌800點。

The explosive speed of the fall ... that is done by machines, said Tom Stevenson, Investment Director at Fidelity Personal Investing.

「下跌的爆炸性速度……是由機器完成的。」富達個人投資的投資總監湯姆史蒂文森說。

Most analysts believe the market tumble was prompted by a report on the US job market, released on Friday, which showed strong wage growth.

大多數分析師認為，股市暴跌是由上周五公布的美國就業市場報告引發的，該報告顯示美國工資增長強勁。

But the decision to sell on that news may have been made by robot traders.

但是，基於這一消息做出賣出決定可能是由機器人交易員的行為。

Trigger point

觸發點

US government bonds, or Treasuries, fell in value after the US jobs report.

美國就業報告公布後，美國政府債券，即美國國債價格應聲下跌。

Yields (the interest that bonds offer investors) rise as prices fall.

收益率(債券為投資者提供的利息)隨著價格下跌而上升。

Its thought that robot traders were waiting for that yield to hit 3% - a significant figure as it could prompt human investors to switch out of shares into bonds.

據認為，機器人交易員正在等待收益率達到3%——這是一個關鍵數字，可能促使投資者將股票轉成債券。

Mr Stevenson said: "Everyone looks for a reason for why the fall happened. One of them was that bond yields rose up towards the magic number of 3%.

史蒂文森表示:「每個人都在尋找出現下跌的原因。其中之一就是債券收益率朝3%這個神奇數字攀升。

There seems to have been a trigger at 2.9% for automatic trading to sell and once that trigger was pulled the markets went into freefall. 「

似乎有一個觸發點是2.9%，達到該點時，自動交易會進行拋售。一旦觸發，市場就進入自由落體狀態。」

Fear index

恐懼指數

Piers Curran, head of trading at Amplify Trading, explained that algorithms will be set up to react in certain ways to certain situations.

Amplify Trading公司的交易主管皮爾斯·柯倫解釋說，演算法設計時會設定針對特定情況，以特定的方式來應對。

He said: "One might work by a stop loss criteria, selling an asset as it falls to prevent further losses.

他說:「它可能在達到止損標準時啟動，在下跌時賣出資產以防止進一步的損失。」

So if the Dow Jones Index has dropped 5% it may trigger the machine to sell, but if you have a huge number of these algorithms hitting stop losses at the same time that produces further falls which produce further stop losses.

因此，當道瓊斯指數下跌5%，可能觸發機器賣出，但如果你有大量的此類演算法，同時達到止損觸發點，那麼就會進一步加劇下跌，從而引發進一步止損。

The algorithmic trading can also be triggered by "correlation" trades, when movement in one market will trigger a trade in a different market.

這種演算法交易也可以由「相關性」交易觸發，即一個市場的波動會觸發另一個市場的交易。

Last week an Index called the VIX, nicknamed the Fear Index because it measures stock market volatility, started to rise sharply.

上周，一個被戲稱為「恐懼指數」的波動率指數(VIX)開始大幅上升，它衡量的是股市的波動性。

Mr Currant said: "The VIX was very elevated last week, and doubled on Monday, and because there is often an inverse correlation between the VIX and the Dow Jones Index, the machine trades sold US equities."

柯倫先生表示:「波動率指數上周大幅上升，周一上漲了一倍，因為VIX指數和道瓊斯指數之間往往存在反向相關性，因此，機器交易賣出了美國股票。」

Selling short

賣空

The triggers though can work in the opposite direction.

這些誘因可以向相反的方向起作用。

Many of the algorithms that sold equities on Monday were "selling short", that is selling stocks specifically to buy them back cheaper later and net a profit. Steep market falls created by algorithms can create equally steep recoveries.

周一賣出股票的許多演算法都是在「賣空」，即賣出股票，然後再以更低的價格買回股票，從而實現盈利。由演算法引發的市場暴跌也可同樣引發迅速反彈。

Mr Curran said: "The markets were reacting to some very specific numbers on Monday, but they are only one set of figures.

柯倫表示:「周一，市場對一些非常具體的數字做出了反應，但它們只是一組數字。」

"We are going to have to see wages growing strongly in February too and get at least four rises in interest rates this year before we can be sure inflation is going to be that much higher.

他說:「我們將看到，2月份的工資水平會強勁增長，今年至少會有4次加息，之後才能確定通脹率是否會有那麼高。」

The market reaction to these single numbers was massively exaggerated because of the machine trades."

因為機器交易，市場對這些單一數字的反應被嚴重誇大了。」

Mr Stevenson agreed: "Algorithmic trading or quant trading does make markets more volatile."

史蒂文森表示同意:「演算法交易或定量交易確實會讓市場變得更不穩定。」

Longer term Mr Stevenson is not pessimistic. "There are two things that can cause a proper bear market - interest rates rising faster than expected, or a recession," he said.

更長期來看，史蒂文森先生並不悲觀。他說:「有兩件事可以引發熊市——利率上升速度超過預期，或者經濟衰退。」

Rates may rise a little faster but not excessively so. As for a recession, all the evidence, bearing in mind the strength of the US economy, is against it.

利率上升得可能會快一些，但不會太快。至於經濟衰退，所有證據都表示，美國經濟仍然勢頭強勁，這一天還不會到來。