A gunman killed one person and wounded four others in an ethnically diverse area outside Paris, in what authorities suspect was a terrorist attack. The incident triggered immediate selling across U.S. equities, with the Nasdaq Composite dropping 2.6 percent to $26,009.

Major technology stocks bore the brunt of the decline. Nvidia fell 4.4 percent to $212.21, while Meta Platforms declined 7.0 percent to $648.85. Amazon dropped 4.6 percent to $250.38. The sharp moves in these high-beta names reflect investor concern about European revenue exposure and discretionary spending.

The S&P 500 retreated 1.2 percent to $7,663. The Dow Jones Industrial Average remained flat at $52,868, suggesting a rotation into defensive names. Apple gained 1.2 percent to $348.22.

French President Emmanuel Macron is expected to address the nation later today regarding the attack and the government's response. Further escalation of security measures or terror declarations could pressure equities into next week's trading. Watch for Eurozone consumer confidence and retail sales data to gauge the economic impact on U.S. companies with significant European operations.