Dimming prospects for a US-China trade deal and sinking US Treasury yields weighed on Wall Street Monday, sending major indices down more than one percent.
The New York trading hub suffered a bruising session after bourses in London, Paris and Frankfurt all declined, with the mushrooming crisis in Hong Kong another negative catalyst.
Analysts said the latest escalations between Washington and Beijing on trade marred sentiment, contributing to a flight from risky assets and towards traditional safe havens like gold.
Goldman Sachs said last week's maneuvers suggested the fight "appears to have escalated into a full-blown conflict," adding in a report that they no longer expect a trade deal between Beijing and Washington before the 2020 presidential election.
Goldman said the hit from lower capital spending due to the trade war could hit US growth by an additional 0.1 to 0.2 percent, an estimate of the "total uncertainty and sentiment drag," said the note.
The yield on the 10-year US Treasury, often seen as a barometer of expectations for future economic growth, slumped sharply.
Other factors weighing on stocks included mounting unrest in Hong Kong that shuttered the airport, an upset victory in an Argentina primary election by populist center-left candidate Alberto Fernandez that slammed the peso, and a mushrooming political crisis in Italy and expected no-confidence vote on the government.
"China is still in the epicenter of the turmoil, with the lingering trade tensions and the escalating protests in Hong Kong both weighing on risk assets globally," Gorilla Trades strategist Ken Berman said in a commentary.
In Hong Kong, the abrupt shutdown came as the Chinese government signaled its rising anger at the protesters, denouncing some of the violent demonstrations as "terrorism," while Washington urged "all sides" to refrain from violence.
City authorities said they were aiming to reopen the airport by 6:00 am Tuesday (2200 GMT Monday), but hundreds of protesters remained in the arrivals hall well into the night, with no sign that they were planning on leaving.
Hong Kong's main shares index closed lower just as news of the shutdown emerged.
Hong Kong airline Cathay Pacific meanwhile on Monday warned staff that they could be fired for supporting "illegal protests," as the firm comes under pressure from Beijing.
The carrier's stock slumped more than four percent after Beijing imposed new rules banning airline staff involved in the protests from flights to or over the mainland.
In Argentina, meanwhile, the peso and the Buenos Aires stock exchange plummeted after a crushing defeat for President Mauricio Macri in party primaries over the weekend.
- Key figures around 2050 GMT -
New York - Dow: DOWN 1.5 percent at 25,896.44 (close)
New York - S&P 500: DOWN 1.2 percent at 2,882.70 (close)
New York - Nasdaq: DOWN 1.2 percent at 7,863.41 (close)
London - FTSE 100: DOWN 0.4 percent at 7,226.72 (close)
Frankfurt - DAX 30: DOWN 0.1 percent at 11,679.68 (close)
Paris - CAC 40: DOWN 0.3 percent at 5,310.31 (close)
EURO STOXX 50: DOWN 0.2 percent at 3,326.55 (close)
Hong Kong - Hang Seng: DOWN 0.4 percent at 25,824.72 (close)
Shanghai - Composite: UP 1.5 percent at 2,814.99 (close)
Tokyo - Nikkei 225: Closed for a public holiday
Euro/dollar: UP at $1.1217 from $1.1200 at 2100 GMT on Friday
Pound/dollar: UP at $1.2076 from $1.2033
Euro/pound: DOWN at 92.84 pence from 93.08 pence
Dollar/yen: DOWN at 105.28 yen from 105.62 yen
Brent North Sea crude: UP 0.1% at $58.57 per barrel
West Texas Intermediate: UP 0.8% at $54.93 per barrel