Market crashes are far more common in our imagination than in reality. This is because they are vivid and scary events. Given our evolution, we are wired to worry about these sorts of vivid events. While, this may have been useful in helping us avoid getting eaten by tigers, it's less useful for rational, disciplined stock market investing. By thinking this topic through now, hopefully you're a little better prepared when the next crash hits.

The stock market crash of October 1929 led directly to the Great Depression in Europe. When stocks plummeted on the New York Stock Exchange, the world noticed immediately. Although financial leaders in the United Kingdom, as in the United States, vastly underestimated the extent of the crisis that would ensue, it soon became clear that the world's economies were more interconnected than ever. The effects of the disruption to the global system of financing, trade, and production and the subsequent meltdown of the American economy were soon felt throughout Europe.[39]

You might be wondering if we’ve endured one too many ghost apparitions. To suggest that no less than Warren Buffett, whose net worth is north of $80.0 billion, expects the market to reverse its bullish course seems not just scary, it seems silly. But Warren Buffett’s predictions for 2018 call for at least a market correction—if not an outright crash.
You can cushion the effects of a crash by allocating to defensive and blue-chip stocks, bonds, gold and cash. Having some cash in your portfolio also allows you to buy back into the market at lower levels. The current stock market is fairly expensive, but there are no signs of an imminent crash. However, that doesn’t mean market conditions can’t change quickly. That’s why you should always be ready for the next crash.
Likewise, stock prices have defeated all forecasting efforts, and may well belong to the same set of basic unpredictability. While occasionally somebody may seem to be on the right side of an investment ahead of a big move, this is a far cry from actually forecasting such move with any kind of precision in terms of timing and size. For each “hunch” that is successful, a myriad others fail. Despite anecdotes, there seems to be no clear evidence that investors who get a big move “right” are anything but lucky.
The increase in internet trading also led to the crash of 2000. The internet served an easy access to trading for a lot of traders who lacked the required experience. Their trial and error methods of trading lead to losses in the stock trading market. Another supposed reason is that the research firms had a conflict of interest. The investment bankers had the research firms put not so honest ratings on the stocks, thus leading to an overall loss of wealth in the market.
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