I'm using Log chart on monthly time frame. Dow Jones Industrial currently trading in very similar fashion of how price action looked before Dot-com bubble.
Index must break 27000$ and trade above it for a while in order to continue higher. If we cannot get above recent top, more choppy action to follow based on almost identical structure we've seen before.
If we cannot break higher of this blue box, 40% drop might follow. If that's the case, test of 2014-2015 lows might occur and give as 15500-16000$.
This is pure speculation and just an idea to look at..