An unprecedented blank check from the Federal Reserve and the prospect of a $1.8 trillion stimulus package from Congress failed to slow a two-week stock purge as investors grasped for signs that progress is being made against the coronavirus.

Stocks plunged around the world, oil tumbled and the stress in U.S. credit markets deepened after the World Health Organization called the coronavirus spread a pandemic and the Trump administration remained unable to detail any stimulus measures to combat the economic fallout.