The US stock market experienced a downturn on March 3, 2026, as the S&P 500 fell 1.02% to 6,810, driven by escalating tensions in the US-Iran conflict and a spike in oil prices. Brent crude briefly surged toward $85 per barrel, exacerbating inflation fears and reducing expectations for Federal Reserve rate cuts. The Strait of Hormuz remains effectively closed, impacting global oil supply, while Iraq has halted production at the Rumaila oil field amid military activity. Market breadth was notably poor, with 73.6% of stocks declining, yet investor sentiment remained surprisingly bullish. The Communication Services sector showed resilience, while Basic Materials suffered the most significant losses. MongoDB shares plummeted 20% following disappointing growth guidance, highlighting the market's sensitivity to forward-looking statements amid broader economic uncertainties.