Jeremy Siegel, finance professor at the University of Pennsylvania's Wharton School, recalls that he will never forget the 1987 stock-market crash.
"It was like a freight train ran everyone down," Siegel told CNBC. "That was the biggest one-day drop in history. It was double the next highest … There has been nothing like it before or since that date," he said.
The S&P 500 fell over 20 percent on the “Black Monday” crash of Oct. 19, 1987, while the Dow Jones Industrial Average slumped by 508 points, or 22 percent.
The 1987 crash is famously now known as a buying opportunity. The Dow industrials recovered in two years to reach previous highs reached in August 1987, Reuters reported.
Despite several rough periods for markets since, most notably the 2008-2009 financial crisis and the bursting of the 2000 dot-com bubble, the sheer magnitude of the one-day fall hasn’t been approached.
Now, if a 22-percent decline were to occur, trading would be halted on the New York Stock Exchange for at least one hour and possibly for the rest of the day, depending on what time such a plunge occurred.
He explained how investors falsely believed they were insured against a market drop through the use of "portfolio insurance" products, which exacerbated the decline.
"What's really amazing a huge percent of crashes occur in the month of October," he said. That's "puzzling why October is seemingly the worst month."
(Newsmax wire services contributed to this report).
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