The US stock market went parabolic late in 2017 and into the first three weeks of January 2018. It sharply corrected. But that's not that unusual.
But several other peripheral markets also went parabolic and fully crashed just prior to the recent sharp correction: Bitcoin (and other crypto-currencies) and the inverse volatility bets. Both of these 'fringe' bubbles destroyed many $100s of Billions of highly speculative money. These fringe bubble busts occurring in recent weeks/months makes the busted parabolic rise of US stocks somewhat more perilous give the full scope of widespread speculation worldwide. We live in a time of extreme speculation in housing, stocks, bonds, art, crypto-currencies, tech stocks, etc. We indeed live in the time of the "everything bubble."
Add the fact that we have historically high market valuations --- if not THE highest. Stock price to revenue, price to GDP, Cape PE and other valuation indicators are near or at ALL TIME HIGHS. There are a many warning signs.
There are some historical precedence to these kinds of "busted parabola" market situations. See the article below. Be on the look-out for any break of the February low of S&P 2581 in the next few weeks. It could mean a sharp, historic waterfall (crash) event.
From Steven Vannelli at Knowlege Leader Capital:
In the last 40 days, we’ve seen the S&P 500 peak at 2872.87 on January 26. Stocks experienced a 10.16% correction over nine days, and then they bounced back by 7.96% over the next 20 days ending last Friday, March 9. We are now in that seven-day window where stocks need to hold up.