US stocks plummeted due to a court ruling deeming most of President Trump's tariffs illegal, raising concerns about potential $120 billion in refunds. The Nasdaq and S&P 500 fell, and Treasury yields spiked. This adds to existing worries about US debt and a contracting manufacturing sector. Trump plans an emergency meeting to discuss appealing the ruling, while analysts warn of increased financial strain and negative impacts on consumers, with companies like McDonald's noting economic pressure on lower and middle-income groups.

Prepared by Christopher Adams and reviewed by editorial team.