The Dow lost 10%, dropping around 2,350 points, to 21,200.62 in its worst session since 1987.
London recorded its worst day since the 1987 crash and Frankfurt its blackest day since 1989, the year the Berlin Wall fell.
Paris suffered its worst one-day loss ever.
Tokyo entered bear territory, and Sydney saw its worst session since the 2008 global financial crisis.
They included the cancelation of the NCAA basketball tournament, the postponement of the profession baseball, hockey, and soccer seasons, the dimming of the lights on Broadway for a month, and the closure of Disney's big amusement park in California.
"Bottoming is a process, it's not a one-day process," said Quincy Krosby, chief market strategist for Prudential Financial.
"Now the idea of a recession is part of the narrative. Are we going into one? And if we are, how deep will it be? Will we have a recovery in the second half?"
Adding to the unease: United States President Donald Trump's shock announcement to bar travel from Europe for 30 days, which exacerbated already brittle relations between Washington and Brussels and battered airlines on both sides of the Atlantic.
US equities briefly cut their losses after the New York Federal Reserve announced measures to inject an additional $1.5 trillion in cash into financial markets this week and launch a modest quantitative easing program.
But the bounce proved short-lived. Emergency measures announced by the European Central Bank (ECB) also did little to reassure investors.
ECB falls flat
Earlier, the ECB ramped up its super-cheap bank lending program and other stimulus measures, but its failure to lower interest rates sparked further selling.
"Eschewing the old-fashioned and arguably ineffective approach of headline rate cuts, it has instead gone for more QE (bond-buying) and a direct loan program for small businesses," said market analyst Chris Beauchamp of online trading firm IG.
Markets also were unnerved by ECB chief Christine Lagarde saying it was not her job to close the spread between Italian and German government bonds, which investors took as a sign that she may be underestimating the degree of stress in the eurozone financial system.
Airline and travel shares were an especially ugly place as Trump's move removed a key revenue stream from carriers like United Airlines and Delta Air Lines,both of which lost more than 20%.
The bleak outlook for airlines also again weighed on Boeing, which plunged 18.1%, making it again the biggest loser in the Dow.
Shares of Carnival cruise lines plunged 31.2% as it announced it would pause its Princess line for two months.
Oil-linked equities also continued to plummet as crude prices sank to multi-year lows on the dimming demand outlook.
"We are now staring at the whole world going into a lockdown," Vandana Hari, of Vanda Insights, said. "Oil demand can be expected to crash through the floor and all previous projections on oil consumption are now out the door." – Rappler.com