But there is a non-statistical basis for concern: an ominous parallel with the financial environment that prevailed in the weeks leading up to the October 1987 stock-market crash. On that day — Black Monday — the Dow Jones Industrial Average dropped 22.6% in a single session.

U .S. stocks tumbled in early trading on Friday, just hours after President Donald Trump signed an executive order slapping new tariffs on dozens of countries. A weak jobs report worsened investor jitters, revealing a slowdown of hiring over recent months as Trump's previous tariffs took hold.