The yield on the 10-year US Treasury note slid as low as 0.318% - a level unthinkable just a week ago - and German government debt yields set record lows as investors rushed to cut risk assets and snap up safe-havens. Gold briefly topped $1,700 an ounce for the first time since 2012 and is up more than 10% so far this year.
The rout's depth, sparked after Saudi Arabia stunned markets on Sunday with plans to hike oil production sharply following the collapse of the Organization of the Petroleum Exporting Countries' supply-cut agreement with Russia, unnerved investors.
"The oil price plunge adds a huge disruptive dynamic to markets that are already very fragile," said Paul O'Connor, multi-asset head at Janus Henderson in London.
"We are seeing this week, finally, a full-scale liquidation and signs of capitulation, full-scale panic - we see this in every asset," O'Connor said.
Jim Vogel, interest rate strategist at FHN Financial in Memphis, Tennessee, said that "nobody thought that Saudi Arabia would start a price war. Suddenly you have to re-evaluate what else could impact this."
Saudi Arabia's grab for market share was reminiscent of a drive in 2014 that sent prices down by about two-thirds, while the renewed plunge on Wall Street came exactly 11 years after US stocks touched bottom during the financial crisis.
Brent and US crude futures slid $14 a barrel to as low as $31.02 and $27.34 in volatile trade. Both crude benchmarks recouped some losses but still fell almost 25% in their biggest daily drop since 1991, the start of the first Gulf War.
Brent fell $10.91 to settle at $34.36 a barrel, while US crude settled down $10.15 at $31.13 a barrel.
The Dow fell a record 2,000 points when trading opened and the S&P 500 was poised for its largest single-day percentage drop since December 2008, the depths of the financial crisis. The benchmark index was almost 19% below its all-time high of February 19 - just 1 percentage point shy of bear territory.
Equity markets in Frankfurt and Paris tumbled about 8.5% and London tanked 11%. Italy's main index slumped 14.3% after the government over the weekend ordered a lockdown of large parts of the north of the country, including the financial capital, Milan.
The pan-regional STOXX 600 fell into bear market territory from an all-time high in February. Oil stocks bore the brunt of losses, with energy giants BP 19.5% lower and Royal Dutch Shell off 18.2%.
The energy sector in Europe was at lowest since 1997. The losses in Europe followed sharp declines in Asia. MSCI's broadest index of Asia-Pacific shares ex-Japan lost 4.4% in its worst day since August 2015 and Japan's Nikkei dropped 5.1%. Australia's commodity-heavy market closed down 7.3%, its biggest daily fall since 2008.
Investors piled into safe-haven debt, driving the 30-year US Treasury yield below 1% on bets that the Federal Reserve will cut interest rates by at least 75 basis points when policy-makers meet next week. The Fed last week cut rates by half a percentage point after an emergency meeting.