NEW YORK, New York - Wall Street endured a sharp sell-off on Monday as jubilation over a Supreme Court decision striking down a core set of Trump-era tariffs gave way to fresh anxiety over the White House's retaliatory trade policies.

The Dow Jones Industrial Average bore the brunt of the selling, plunging 821.91 points, or 1.66 percent, to close at 48,804.06.

The broader Standard and Poor's 500 fell 71.76 points, or 1.04 percent, settling at 6,837.75, while the tech-heavy Nasdaq Composite dropped 258.79 points, or 1.13 percent, to finish at 22,627.27.

The market turmoil comes on the first day of a new trade regime following last week's seismic Supreme Court ruling. On Friday, the high court voted 6-3 to void most of the sweeping tariffs President Donald Trump had imposed in 2025, finding that the administration had overstepped its authority by using the International Emergency Economic Powers Act (IEEPA) to justify the levies .

In compliance with that ruling, the U.S. Customs and Border Protection agency officially halted the collection of those specific duties as of 12:01 a.m. on Monday . The decision puts more than $175 billion in collected tariff revenue at risk for potential refunds to importers .

However, any investor optimism over the removal of those tariffs was quickly overshadowed by President Trump's defiant response. Within hours of the court's decision, the President announced a new, 15 percent global tariff on all countries, invoking a different legal authority—Section 122 of the Trade Act of 1974 . This new levy, which went into effect Monday, is designed to temporarily replace the struck-down duties but can only remain in place for 150 days unless extended by Congress .

"The uncertainty is the real killer for markets right now," said analysts following the moves. "It's really hard from a business standpoint when you are at a company to know how do you plan if you're not even sure about suppliers, supply chains and what the tariffs are going to look like," noted Arthur Laffer Jr., president of Laffer Tengler Investments, highlighting the confusion facing corporate America .

The whipsaw in trade policy left investors grappling with the implications of a 15 percent import tax and the potential for retaliatory measures from U.S. trading partners. While the initial Supreme Court ruling was seen as a check on executive power, the rapid implementation of new tariffs under a different statute has reignited fears of a protracted trade war.

U.S. Dollar Mixed as Yen Euro and Pound Gain Monday, Commodity Currencies Slide

The U.S. dollar presented a mixed picture against major peers in Monday trading, gaining ground against safe-haven and commodity-linked currencies while slipping against the euro and British pound.

The euro strengthened against the greenback, with the EUR/USD pair rising 0.11 percent to settle at 1.1790. The modest gain for the common currency comes as traders digest the latest economic data out of the Eurozone.

The British pound also posted gains. GBP/USD climbed 0.15 percent to trade at 1.3490, extending a recent run of resilience for the sterling amid shifting expectations for Bank of England interest rate policy.

The dollar also weakened against the Japanese yen. The USD/JPY pair fell 0.21 percent to 154.70. The movement reflects a slight uptick in demand for the yen as a safe haven, despite the broader strength in U.S. yields.

The Swiss franc, another traditional safe haven, also edged higher against the U.S. dollar. USD/CHF dipped 0.07 percent to 0.7743.

Commodity-linked currencies were the day's biggest laggards. The Australian dollar fell slumped, with AUD/USD dropping 0.35 percent to 0.7055. The New Zealand dollar followed a similar path, as NZD/USD declined 0.28 percent to 0.5954. The moves come amid fluctuating prices for key commodities and shifting sentiment toward the Chinese economy, a major trading partner for both nations.

In North America, the Canadian dollar weakened against its U.S. counterpart. The USD/CAD pair rose 0.18 percent to 1.3698, as the loonie struggled despite ongoing stability in oil prices.

Global Stock Markets End Mixed Monday as Tech Worries Weigh on Europe, Egyptian Index Surges

Global stock markets presented a mixed picture in Monday's trading, with European bourses succumbing to losses while several Asian indices posted solid gains, led by a surge in Hong Kong and a record-breaking rally in Egypt.

In Canada, the S&P/TSX Composite index fared slightly better than its U.S. counterparts but still ended in negative territory. The index slipped 41.01 points, or 0.12 percent, to close at 33,776.50, as the country's energy and materials sectors weighed on the broader market amid the renewed trade tensions.

In Europe, sentiment was dampened by ongoing concerns over interest rates and a pullback in technology shares, dragging major benchmarks into the red. The pan-European EURO STOXX 50 Index fell by 0.28 percent, closing at 6,113.92, while the broader Euronext 100 Index slipped a marginal 0.05 percent to end the day at 1,833.23.

Germany's DAX was the worst performer of the major European indices, dropping 268.72 points, or 1.06 percent, to settle at 24,991.97. France's CAC 40 also retreated, losing 0.22 percent to close at 8,497.17.  Belgium's BEL 20 index fared worse, shedding 0.88 percent to end at 5,605.19.

London's FTSE 100 managed to hold relatively steady, edging down just 2.15 points—a negligible decline of 0.02 percent—to finish at 10,684.74.

The negative trend was less pronounced in Asia, where several markets rallied. In a strong showing, Hong Kong's HANG SENG INDEX jumped 668.56 points, a robust gain of 2.53 percent, to close at 27,081.91. Indonesia's IDX COMPOSITE also saw significant buying interest, climbing 1.50 percent to 8,396.08.

On the other hand, China's SSE Composite Index struggled, falling 1.26 percent to 4,082.07, reflecting ongoing economic headwinds in the region.

Elsewhere in the Asia-Pacific region, gains were more modest but widespread. Japan's Nikkei 225 was a notable exception, falling 1.12 percent to 56,825.70. However, Australia's S&P/ASX 200 declined 0.61 percent to 9,026.00, while the broader ALL ORDINARIES index was down 0.56 percent to 9,251.50.

In Singapore Monday, the STI Index bucked the regional trend to the downside, adding 0.47 percent to finish at 5,041.33.

India's S&P BSE SENSEX continued its upward trajectory, gaining 0.58 percent to close at 83,294.66.

South Korea's KOSPI Composite Index rose 0.65 percent to 5,846.09, and Taiwan's TWSE added 0.50 percent to end at 33,773.26.

In Malaysia the FTSE Bursa Malaysia KLCI posted a modest gain of 0.29 percent to 1,757.98, while New Zealand's S&P/NZX 50 climbed 0.84 percent to 13,420.43.

In a standout performance, the EGX 30 Price Return Index in Egypt soared, jumping 1,309.20 points, or 2.64 percent, to close at 50,870.10, marking a significant gain for the North African market.

(This report incorporates quotes retrieved with the assistance of artificial intelligence).

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