...how about an Oct 1987 style plunge?
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Black Monday (1987)
From Wikipedia, the free encyclopedia DJIA (19 July 1987 through 19 January 1988).
FTSE 100 Index (19 July 1987 through 19 January 1988).Black Monday is the name given to Monday, October 19, 1987, when the Dow Jones Industrial Average (DJIA) fell dramatically, and on which similar enormous drops occurred across the world. By the end of October, stock markets in Hong Kong had fallen 45.8%, Australia 41.8%, the United Kingdom 26.4%, the United States 22.68%, and Canada 22.5%. (The terms Black Monday and Black Tuesday are also applied to October 28 and 29, 1929, which occurred after Black Thursday on October 24, which started the Stock Market Crash of 1929.)
The Black Monday decline was the second largest one-day percentage decline in stock market history. The largest one occurred on Saturday, December 12, 1914, when the DJIA fell 24.39%. However, in that case, the New York market had been closed since July due to the outbreak of the First World War. The greatest point loss in DJIA history was on Monday, September 17, 2001, 684.81 points, six days after the September 11, 2001 attacks and the first day after which the market was open.
A certain degree of mystery is associated with the 1987 crash. Many have noted that no major news or events occurred prior to the Monday of the crash, the decline seeming to have come from nowhere. Important assumptions concerning human rationality, the efficient market hypothesis, and economic equilibrium were brought into question by the event. Debate as to the cause of the crash still continues many years after the event, with no firm conclusions reached.
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http://en.wikipedia.org/wiki/Black_Monday_(1987)