In the United States, the tech-heavy Nasdaq Composite Index plummeted by 4 percent, seeing its worst day since 2022 after Trump declined to rule out the risk of a US recession.
The S&P 500 dropped 2.7 percent to drag it close to 9 percent below its all-time high, which was set just last month.
The Dow Jones Industrial Average dropped 890 points, or 2.1 percent, after paring an earlier loss of more than 1,100.
Since taking office in January, Trump has imposed sweeping tariffs on imports from Canada, Mexico and China – before allowing a partial rollback for the two US neighbours.
A new wave threatens to arrive this week, with steep levies of 25 percent on steel and aluminium imports due to take effect on Wednesday.
The Nasdaq was bogged down by retreats in the so-called Magnificent Seven tech stocks, which include Google parent Alphabet, Apple, Amazon, Meta and Nvidia.
Stocks in electric carmaker Tesla, led by Trump’s billionaire advisor Elon Musk, closed more than 15 percent down.
The yield on the 10-year Treasury tumbled again to 4.22 percent from 4.32 percent late on Friday. It’s been dropping since January, when it was approaching 4.8 percent, as worries about the economy have grown.
The London, Paris and Frankfurt stock markets all closed lower. (Agencies)
