Hopefully this isn't a biased take: I think this is a unique situation because the recent moves (in my opinion) are largely a result of everyone's uncertainty around America's policies. In other words, the recent stock moves aren't because we're seeing a bunch of companies fail to miss quarterly targets. There are no major economic indicators flashing red. If stocks can drop that fast in a couple weeks, they can also…
1. Trump is planning to deflate the dollar (not the least of which being that this his Secretary of Treasury wrote a plan to do this); 2. Trump might be planning to re-negotiate the US debt, for what I believe is the first time in history.
Neither is the kind of thing that the markets enjoy seeing. After all, if the dollar is deflated by 50% (I'm inventing that number), all the money invested in Wall Street suddenly loses 50% of its value.
Also, I've read a few economists, and they seem to agree that the prosperity of the US is largely a bubble based on the (artificially) strong dollar, but that the same strong dollar is killing US exports. By these accounts, Trump's maneuvers are an attempt to pop that bubble, which might be good, but will destroy the prosperity bubble, which nobody really wants. Whether it's true or not, that hypothesis is a good reason to not invest in US economy.
And none of these three points can be fixed easily.