I was reading on a more wonky site that a lot of the current turmoil has to do with Japan raising its interest rates and pretty much nothing to do with market fundamentals in the US. Japan's interest rates were near zero, and it was apparently a common practice to borrow money cheaply in Yen, and then invest it in higher yielding assets. Margins are slim, so as soon as the central bank raised interest rates in Japan and the Yen surged in strength, the scheme became unviable. Large institutional investors across the globe are now unwinding their investments simultaneously and covering, causing a massive sell-off.
Not saying it won't turn into a broader contagion that could start to collapse the markets; it could. But it appears the immediate downturn is (as usual) due to large scale investment into esoteric financial schemes to make a quick buck, and then being caught flat-footed when the environment changed and made those schemes unviable. Not due to any panic over what US politicians may or may not attempt to do in a year or more time. And not due to normal fluctuations in the US employment rate (which remains historically low). *
It could also be a short-term sell-off that the world collectively shrugs off once the unwinding is complete. I'm no market guru insider; I have no idea how exposed the world is to this mess.
*I realize lawpoke didn't assert this, but certain US politicians and pundits have, and so it seemed worth mentioning.