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.

Stocks across the globe closed lower Friday after President Donald Trump unveiled his plan for levying tariffs on trading partners, threatening to upend decades of international cooperation.

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.