It got my attention too. I don't know what investors are thinking because the predictions they made yesterday didn't account for today. I'm not a Wall Street pro by any means but reading their predictions for 2019 makes me think not even they have any idea because they are all over the place.
The Wall Street Journal had an opinion piece this afternoon that opened with this. My inclination is to believe the chaos and incoherence of this administration has spooked everyone:
Financial savants were quick to lambaste Federal Reserve Chairman Jerome Powell last week for failing to reassure markets that the Fed would ease off on increasing interest rates next year. Some pundits also denounced Mr. Powell’s “disastrous” performance at the press conference following the rate hike. One awarded him an F for diffident delivery and confused “messaging.”