????還記得那次閃電式大崩盤嗎？2010年5月6日，道瓊斯工業平均指數在短短幾分鐘內暴跌600點。市值達1,650億美元的消費品巨頭寶潔（Procter and Gamble）在幾秒鐘內就遭受了37%的損失。埃森哲（Accenture）和愛克斯龍（Exelon）跌至每股1美分。所有股票齊齊跳水。

????然而在接下來的一瞬間，一切又都恢復了正常。市場收復了幾乎所有失地。問題是，沒有人能解釋剛剛發生了什么。就算你是摩根士丹利（Morgan Stanley）的大客戶也沒用，就是沒有答案。

????記者最終還原了整個事件的原委。原來，堪薩斯州的一家共同基金公司在期貨市場做了一份賣空，因此引發了拋售的連鎖反應。在某些方面，這種解釋比我們之前一無所知的狀態更可怕。難道美國股市已淪落到這種地步嗎？一只堪薩斯州的蝴蝶扇動了一下翅膀，就會導致整個股市崩盤嗎？

????在《暗池交易》（Dark Pools）一書中，《華爾街日報》（Wall Street Journal）的記者斯科特?帕特森解釋了我們陷入這場混亂的原委。有個問題已經在華爾街蔓延十多年了，而閃電崩盤只不過是它最主要的癥狀。高速交易員，也被戲稱為高頻交易員，因為他們每秒進行的股票買賣能達到數千次，遠遠超過股市。

????一方面，他們提供持續的流動性，使得普通投資者不用向納斯達克或紐約證券交易所的中間商（所謂的做市商）支付驚人的價差。另一方面，他們的不透明技術已為我們上演了諸如閃電崩盤的慘劇。

????作為一名長于數學的財經記者，帕特森善于深挖有關高速交易——華爾街新寵——的生動報道。他的上一本書《寬客》（2010年）詳盡描述了量化交易員的全新世界，他們利用計算機算法來處理交易中的苦差事。而在《暗池交易》中，他則瞄準了市場上的跳水現象，在這個過程中，寬客可以在幾微秒（百萬分之一秒）內進行股票買賣。

????這種跳水最初由紐約斯塔騰島區的交易員和編程怪才喬希?萊文建立，他們形成的聯盟看起來有些另類。最后，天體物理學家也加入進來。他們合力把美國股市改造成了超出前人想像的高速機器。

????Remember the flash crash? On May 6, 2010, the Dow Jones Industrial Average plunged by 600 points over a couple of minutes. Procter and Gamble (PG), the $165-billion consumer giant, lost 37% of its market cap within seconds. Accenture (ACN) and Exelon (EXC) dropped to a penny a share. All hell seemed to be raining down.

????In the next instant, everything was back to normal. The market regained almost all of its losses. Problem was, no one could explain what had just happened. It didn't matter if you were Morgan Stanley's favorite client, there just weren't answers.

????Journalists eventually pieced the story together. It turned out that a mutual fund company in Kansas had set off a chain reaction of selling by placing a single order in the futures market. In some ways, this explanation was more terrifying than our previous state of ignorance. Had the U.S. stock market come to this? Crashing because a Kansas butterfly flapped its wings?

????In Dark Pools, Wall Street Journal reporter Scott Patterson explains how we got into this mess. The Flash Crash was the first major symptom of a problem that has been spreading across Wall Street for more than a decade. High-speed traders, dubbed high-frequency traders because they trade in and out of stocks thousands of times per second, have overtaken the stock market.

????On the one hand, they provide constant liquidity so regular investors don't get charged egregious spreads by middlemen -- the so-called market makers -- at Nasdaq or the New York Stock Exchange. On the other, their opaque technology has given us episodes like the Flash Crash.

????Patterson, a wonderfully numerate financial journalist, is good at ferreting out vivid stories about high-speed trading, the Street's newest infatuation. His previous book, The Quants (2010), was a rich narrative about the new world of quantitative traders -- guys who let computer algorithms do the hard work of trading. In Dark Pools he zeros in on the market plumbing that has allowed quants to jump in and out of stocks in microseconds (millionths of a second).

????The plumbing was first built by an unlikely alliance between Staten Island traders and a programming nerd named Josh Levine. Eventually astrophysicists joined in. Together, they retooled the U.S. stock market into a speed machine unlike anything ever imagined.