Kennedy Slide of 1962
Also known as the Flash Crash of 1962, this crash happened between December 1961 and June 1962, and although never directly attributed to any source, it was thought to be because of quick changes in investor sentiment.
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The Slide resulted in a 27% fall in the stock market’s value, and the S&P index would fall by close to 23%. No other causes for the event could found, other than inflated stock prices and failing investor confidence.