Cory Mitchell 2016年1月11日
“闪电崩盘”一词在2010年5月6日标准普尔500在不到15分钟内狂跌7%然后快速反弹之后迅速流行。这是由于个股闪电崩盘引起的。例如，埃森哲股价到达0美元，但是仅以略低于开盘的41.09美元收盘。这一现象在现在仍然存在，2015年就发生过在几分钟内价格暴跌的闪电崩盘事件。
2015年8月24日，星期一
许多交易者对这天的印象非常深刻。标准普尔500指数以1965.15点开盘，但是在几分钟内跌到1867.01的低点，跌幅为5%。当天市场回升也非常巨大，几乎返回到了原来的水平，但是收盘之前股票再次下跌，收盘时比开盘下跌3.66%。
抛售是一系列因素影响的结果。主要的催化剂是8月20日和21日已经有过大量的抛售，使投资者在周末非常小心。亚洲市场开盘时间在美国市场之前，周一上午，中国上证综合指数下跌8.5%，这导致美国市场交易者停止买入并开始抛售。因为几乎没有买入订单，而卖出订单太多，所以价格持续下跌。
根据美国全国广播公司财经频道的报道，由于缺少买入订单，纽约交易所的许多股票延迟开盘。由于一些股票能交易而一些不能，所以不能得到ETF和期货产品的公允价值。这引起了进一步的动荡，使得交易者在这天开始的时候卖出增加买入减少。
随着交易的进行，许多交易者停止进入市场，价格逐渐稳定。标准普尔500最终逐渐从8月24日的低点反弹并在2015年以2043.94点结束。
2015年3月28日，星期三
当天闪电崩盘对交易美元的交易者产生了巨大影响，在四分钟内美元价值下跌3%。然而，在接下来的几分钟美元恢复了大部分价值。依赖欧元/美元汇率的欧元外汇期货在五分钟内经历了四年来最大的价格波动。
欧元/美元现货货币对下午四点时汇率为1.0837，在没有特殊刺激的情况下在五分钟只能上升到了1.1040的高点，上涨接近2%。主要货币通常在一天内波动小于1%，因此几分钟之内几个百分点的波动十分不正常，尤其是在当天没有新闻刺激的时候。
闪电崩盘发生在美国东部时间下午4：04，股票市场收盘后的四分钟。美国东部时间下午两点召开了联邦公开市场委员会会议，由于延迟加息消息的发布使股市暴涨。道琼斯工业平均指数收盘时上涨1.8%，ICE交易所的美元期货下跌水平大致相同。在下午四点收盘之后道琼斯工业平均指数期货保持平稳，而美元期货继续下跌，比下午四点时下跌3%。
总结
闪电崩盘还在发生，上面两个是2015年的主要案例。8月24日的闪电崩盘引起了许多媒体的关注，也许是因为发生的时间的特殊性和许多散户投资者受到影响。3月18日的美元闪电崩盘几乎没有引起媒体关注，因为其发生时间是在正常市场时间之外并且受影响的大多数是活跃交易者和机构交易者，而不是散户交易者。无论谁受到影响，发生闪电崩盘总是让人不安的。无论事件得到关注与否，闪电崩盘对所有金融市场交易者和投资者都有很大风险。
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.
本文翻译由兄弟财经提供
文章来源：http://www.investopedia.com/articles/investing/011116/two-biggest-flash-crashes-2015.asp