Panic in one big market leads other traders to act like a scared herd of gazelles, running frantically for fear of a lion even if they have no idea what or where the danger is.
First, it reaches institutional and individual investors who are active traders, the first ones to receive and act instantly on the information (the innovators and the early adopters in Rogers Curve).
Conifer's Mr. Fier noted that stock futures actually flickered lower after the positive labor data, a sign that traders worry that positive data will increase the likelihood for the Fed to act soon.
That left traders scrutinizing the post-meeting statement for clues on how policymakers view the economy and therefore how they might act down the road.
Then you have a Congressional hearing starring self-indulgent, preening traders from guilty as hell organizations testifying that they had no idea all this was coming, that it was an act of nature and the reason they did so well was they just know more and therefore still deserve their bonuses.