The US stock market tacked on roughly $1.15 trillion in market value in a single trading session. The rally was broad but not random: AI-adjacent stocks and semiconductor names did most of the heavy lifting, while positive signals on the US-Iran front gave investors permission to buy aggressively.
The Nasdaq climbed approximately 2.4% on the day, with the S&P 500 gaining about 1.8%. Both indices pushed to record highs, extending a run that has seen the S&P 500 add trillions in total market cap since its March 2026 lows.
What drove the surge
Two forces converged. First, the AI trade that has defined markets for the past two years showed no signs of fatigue. Semiconductor stocks continued pulling capital from virtually every other sector. Second, geopolitical optimism gave risk appetite a jolt, with investor sentiment lifting after statements from former President Trump regarding Iran.
Throughout 2026, markets have experienced single-session swings ranging from $650 billion to $1.7 trillion across the S&P 500.
