Cory Mitchell 2016年1月11日
“閃電崩盤”一詞在2010年5月6日標準普爾500在不到15分鐘内狂跌7%然後快速反彈之後迅速流行。這是由於個股閃電崩盤引起的。例如，埃森哲股價到達0美元，但是僅以略低於開盤的41.09美元收盤。這一現象在現在仍然存在，2015年就發生過在幾分鐘内價格暴跌的閃電崩盤事件。
2015年8月24日，星期一
許多交易者對這天的印象非常深刻。標準普爾500指數以1965.15點開盤，但是在幾分鐘内跌到1867.01的低點，跌幅為5%。當天市場回升也非常巨大，幾乎返回到了原來的水平，但是收盤之前股票再次下跌，收盤時比開盤下跌3.66%。
抛售是一系列因素影響的結果。主要的催化劑是8月20日和21日已經有過大量的抛售，使投資者在週末非常小心。亞洲市場開盤時間在美國市場之前，週一上午，中國上證綜合指數下跌8.5%，這導致美國市場交易者停止買入並開始抛售。因為幾乎沒有買入訂單，而賣出訂單太多，所以價格持續下跌。
根據美國全國廣播公司財經頻道的報道，由於缺少買入訂單，紐約交易所的許多股票延遲開盤。由於一些股票能交易而一些不能，所以不能得到ETF和期貨產品的公允價值。這引起了進一步的動蕩，使得交易者在這天開始的時候賣出增加買入減少。
隨著交易的進行，許多交易者停止進入市場，價格逐漸穩定。標準普爾500最終逐漸從8月24日的低點反彈並在2015年以2043.94點結束。
2015年3月28日，星期三
當天閃電崩盤對交易美元的交易者產生了巨大影響，在四分鐘内美元價值下跌3%。然而，在接下來的幾分鐘美元恢複了大部分價值。依賴歐元/美元匯率的歐元外匯期貨在五分鐘内經歷了四年來最大的價格波動。
歐元/美元現貨貨幣對下午四點時匯率為1.0837，在沒有特殊刺激的情況下在五分鐘只能上升到了1.1040的高點，上漲接近2%。主要貨幣通常在一天内波動小於1%，因此幾分鐘之内幾個百分點的波動十分不正常，尤其是在當天沒有新聞刺激的時候。
閃電崩盤發生在美國東部時間下午4：04，股票市場收盤後的四分鐘。美國東部時間下午兩點召開了聯邦公開市場委員會會議，由於延遲加息消息的發佈使股市暴漲。道瓊斯工業平均指數收盤時上漲1.8%，ICE交易所的美元期貨下跌水平大致相同。在下午四點收盤之後道瓊斯工業平均指數期貨保持平穩，而美元期貨繼續下跌，比下午四點時下跌3%。
總結
閃電崩盤還在發生，上面兩個是2015年的主要案例。8月24日的閃電崩盤引起了許多媒體的關註，也許是因為發生的時間的特殊性和許多散戶投資者受到影響。3月18日的美元閃電崩盤幾乎沒有引起媒體關註，因為其發生時間是在正常市場時間之外並且受影響的大多數是活躍交易者和機構交易者，而不是散戶交易者。無論誰受到影響，發生閃電崩盤總是讓人不安的。無論事件得到關註與否，閃電崩盤對所有金融市場交易者和投資者都有很大風險。
The Two Biggest Flash Crashes of 2015
By Cory Mitchell | January 11, 2016
The term "flash crash" gained popularity in 2010 when on May 6, the S&P 500 declined 7% in less than 15 minutes, and then quickly rebounded. This was driven in part by flash crashes in individual stocks. For example, Accenture (ACN) hit $0, but closed the day at $41.09, which was marginally down from the open. The term stuck, but while 2010 was the "big one," flash crashes still occur today. 2015 brought its share of flash crashes where price plunged in minutes.
Monday, August 24, 2015
This date is embossed on many trader's memories. The S&P 500 opened at 1965.15 and within minutes fell to a low of 1867.01, a 5% decline. Intraday the market gained back most of the loss, but toward the close of trading stocks fell again, ending the day 3.66% below the open.
The sell-off was fueled by a combination of factors. The main catalyst for the selling was that the market had already experienced strong selling on August 20 and 21, leaving investors wary heading into the weekend. Asian markets open before US markets, and on Monday morning, the Chinese Shanghai Composite Index fell 8.5%, which led traders in U.S. markets to pull their buy orders and hit the sell button. With few bids, sell orders overwhelmed any buy order present, pushing prices lower.
Due to the lack of bids, many stocks on the NYSE were delayed in opening, according to CNBC. But with some stocks trading and others not, the fair value of ETFs and futures products couldn't be established. This caused further unrest, causing traders to sell more and bid less in those initial moments of August 24.
As the trading day got underway, more traders stepped into the market, and prices stabilized. The S&P 500 ultimately bounced off the August 24 low and closed out 2015 at 2043.94.
Wednesday, March 18, 2015
This flash crash affected traders who were trading the US dollar, which fell more than 3% in under four minutes according to Nanex. However, most of the loss was erased in the next few minutes. For EUR FX (6E) futures, which are based on the EUR/USD exchange rate—it was the largest price swing within five minutes in the last four years. The Euro can also be traded via the CurrencyShares Euro (FXE) ETF.
The spot EUR/USD exchange rate traded at 1.0837 at 4 p.m. EST and went as high as 1.1040, a nearly 2% move in under five minutes with no specific catalyst. Since spot currency market are not traded on a centralized exchange, the moves seem by some traders could have been much larger based on their broker. Major currencies typically move 1% or less in a day, so a multiple percentage point move in minutes is highly irregular, especially at this time of day and without a news catalyst.
The flash crash occurred at 4:04 p.m. EST, four minutes after the official stock market close. At 2 p.m. EST was a Federal Open Market Committee (FOMC ) meeting, which caused the stock market to rally on news that an interest rate hike would be delayed (it didn't come till December, 2015). The Dow Jones Industrial Average (DJIA) closed the day 1.8% higher, and US dollar futures on the ICE exchange were down about the same. After the 4 p.m. market close the DJIA futures stayed steady, while the US dollar futures plunged, dropping another 3% from the 4 PM price. Little explanation, or even publicity, was given for the sudden move that was swifter than the moves caused by the FOMC announcement earlier in the day.
The Bottom Line
Flash crashes continue to occur, and these were two of the main ones in 2015. The August 24 crash received a lot of media attention, likely because of the time of day it occurred (during the U.S. session) and because it affected so many retail investors. The US dollar flash crash on March 18 received almost no media attention, though, likely because it occurred outside normal market hours and thus mostly affected active and institutional traders, not retail investors. No matter who the flash crash affects, its' worrisome that it happens at all. Such events are the risk all traders and investors take when investing in financial markets, whether the events are publicized or not.
本文翻譯由兄弟財經提供
文章來源：http://www.investopedia.com/articles/investing/011116/two-biggest-flash-crashes-2015.asp