US equities were little changed on Monday after President Donald Trump announced

US equities were little changed on Monday after President Donald Trump announced an increase in global tariffs to 15%, following a Supreme Court ruling that struck down his earlier “reciprocal” tariff framework.

The S&P 500 hovered around the flatline during the session, while the Dow Jones Industrial Average and the Nasdaq Composite also traded with minimal movement.

Investors appeared cautious as they assessed the implications of the new tariff regime for inflation, growth, and corporate earnings.

The move followed a weekend announcement in which Trump said he would raise the global tariff rate from 10% to 15%, adding that the new duties would take effect immediately.

However, it remained unclear whether formal documentation had been signed to confirm the timing.

Tariff announcement and legal backdrop

Trump’s decision came shortly after the Supreme Court of the United States struck down a broad set of his earlier trade measures.

In a post on Truth Social, Trump said: “I, as President of the United States of America, will be, effective immediately, raising the 10% Worldwide Tariff on Countries, many of which have been ‘ripping’ the U.S. off for decades, without retribution (until I came along!), to the fully allowed, and legally tested, 15% level.”

He also warned that additional levies could be introduced in the coming months, raising concerns that trade policy uncertainty may persist.

The tariffs were imposed under Section 122 of the Trade Act of 1974, which allows the president to levy duties for up to 150 days before congressional approval is required. Market participants said this legal framework could continue to generate volatility.

Gold rallies, Bitcoin slides

Commodities and digital assets reflected growing risk aversion following the tariff announcement.

Gold prices jumped as investors sought safety. Spot gold advanced more than 1%, while gold futures climbed around 2%, driven by concerns over inflation and global growth prospects.

Bitcoin, meanwhile, came under pressure. The cryptocurrency fell below $65,000 at one point before recovering above $66,000.

It remained down about 2% on the day, extending a recent sell-off as risk appetite weakened.

The divergence between gold and Bitcoin highlighted a broader shift toward traditional safe-haven assets.

Europe voices concern

Officials in Europe expressed unease over the tariff increase, warning that transatlantic trade relations could be affected.

The European Commission said in a statement on Saturday that “the current situation is not conducive to delivering ‘fair, balanced, and mutually beneficial’ transatlantic trade and investment” and called for “full clarity” from the US government.

The statement reflected growing worries that escalating trade barriers could undermine existing agreements and disrupt supply chains.

Volatility Follows Choppy Session

Wall Street entered Monday’s session following a volatile end to last week.

On Friday, stocks initially rallied after the Supreme Court ruling, as investors anticipated a possible easing of trade tensions and potential refunds for companies affected by earlier tariffs.

However, gains were uneven and fragile, reflecting uncertainty over how the administration would respond.

Trump’s weekend announcement quickly erased hopes that trade risks would recede.

Market participants said policy unpredictability remains a key overhang for equities.

Individual Stock Movers

Several individual stocks recorded sharp moves during the session.

Shares of Arcellx surged 78% after Gilead Sciences agreed to acquire the company for $7.8 billion. The deal includes $115 per share in cash at closing and a contingent value right of $5 per share. Arcellx focuses on immunotherapies for cancer and other incurable diseases, and the transaction is expected to close in the second quarter.

Novo Nordisk shares fell 14% after its weight-loss drug CagriSema failed to match results from a rival treatment developed by Eli Lilly and Company. Lilly’s shares rose nearly 3% following the trial results.

Domino’s Pizza gained 4% after reporting US fourth-quarter sales growth of 3.7%, exceeding a 3.1% estimate compiled by FactSet. Revenue also beat expectations, coming in at $1.54 billion versus a $1.52 billion forecast.

Outlook Remains Uncertain

With higher tariffs now in place and further measures possible, investors remain cautious about the outlook for trade, inflation, and corporate profitability. The combination of legal uncertainty, geopolitical considerations, and shifting policy signals continues to shape market behaviour.

For now, equities appear caught between resilient earnings expectations and rising macroeconomic risks, leaving markets vulnerable to further swings as trade policy evolves.