October 19, 2017 is the 30th year anniversary of "Black Monday" stock market crash (October 19, 1987), on this day stock markets around the world plunged. The Dow Jones Industrial Average fell 508 points marking a 22.6 percent drop, its largest ever one-day drop. The FTSE100 shed 11 per cent; and European markets followed the same downward pattern.
Following the big fall, regulators put new rules into effect, allowing for a halt in trading when there are exceptionally large price drops in certain indexes.
The fall in US markets was twice the size of those during the 1929 market crash (marked by a Black Tuesday and Black Thursday), and greater than any single-day move during the 2008 financial crisis. The recovery was almost as steep as the precipitous declines.
So will it happen again? It's possible since stock market involves risk however that kind of crash is highly unlikely.
Dow Jones industrial average is trading above 23,000 for the first time. It’s been nearly 16 months since S&P 500 index funds had a pullback of even 5 percent over the course of days or weeks, its longest such streak in two decades.
Many analysts expect the market to keep climbing, at least for the next year. The global economy is improving, corporate profits are rising and inflation remains low but not so low that it makes economists nervous.