The attitude of the market makers changed 180 degrees over the weekend. The incompetent and bewildering banning of travel from 7 of 54 (or so) "Muslim" countries stunned the players. Iraq, who is their primary partner in fighting ISIL. And the other 6 have zero connection to terrorism against US assets. 

And he somehow left out all the countries with historic and actual terrorism - Nigeria, Saudi Arabia, Egypt, UAE, Pakistan, etc. Cynics might ask whether the Trump companies have business ties with them. 

Business leaders are wavering in their support of Trump policies - read the news. Republicans are also speaking out. And a majority of US states spoke out as well. 

Business leaders are less confident and a slow down naturally results. This may be the end of the 8 years of expansion since the Global Financial Crisis.