Often when stories like this come out, the market does the opposite. It is a very difficult game to guess which way the crooks actually will take it though.

The S&P 500 represents 500 stocks, the Dow represents 30 stocks, the Nasdaq, 100 stocks, the Russel, 2000 stocks - and because the Russell represents 2000 stocks, it represents a much broader market, it is generally a much, much better gauge of the markets overall and most often the other markets follow it's direction, this makes the Russell a type of leading indicator.  

Since the article was published till now, the markets have not really moved a whole lot.  

So just for fun for future reference, as of the close on 09/10/2018, which is about 3 weeks after the article was published, here are the closing numbers to see which way it actually ends up going, just to check the accuracy of the article's "sell signal":

S&P 2877
Dow 25857
Nasdaq 7924
Russell 1717

I think you missed a key paragraph:
To be sure, Cardiff is quick to emphasize, his risk indicator is not a short-term market timing tool. In the wake of past occasions when it rose above 2.0, for example, equities stayed high or even continued rising “for many months, sometimes even a couple of years.” However, he continues, “in all cases, a major decline or crash followed, pulling down stock prices by 50% or more.”

I actually saw that but it's the same old ploy imo. It's not much of an indicator if it can't really be timed at all, or at least enough to be useful to some extent. I mean honestly, who can use that indicator? When is it best to sell, or buy for that matter using that as an indicator? Anyone can say - "my indicator never fails and it is showing that the market will go down sometime between many months from now to a couple of years". lol  As a "major sell signal", it is extremely lame at best, imo.