S&P 500 and Nasdaq Fall as Tech Selloff Resumes and Trump Vows Iran Retaliation

The Quick Take

• US equity markets declined as tech selling resumed, with S&P 500 and Nasdaq both falling amid escalating US-Iran geopolitical tension
• President Trump vowed to retaliate against Iran following reports of a downed US helicopter, raising fears of conflict escalation
• Upcoming US May CPI data will test whether rising energy prices from the Iran war are feeding into broader inflation measures

The renewed US equity selloff reflects the intersection of two reinforcing pressures: continued tech sector valuation concerns following an extended AI-driven rally, and escalating US-Iran conflict risk after the downed helicopter incident. The S&P 500 and Nasdaq — where large-cap tech companies like Apple, Microsoft, NVIDIA, and Alphabet represent over 30% of index weight — remain particularly vulnerable to any catalyst that reprices growth expectations. Trump's vow to respond militarily creates a geopolitical risk premium that historically triggers defensive rotation from growth stocks toward energy, defense, and gold.

Defense contractors like Lockheed Martin, Raytheon, Northrop Grumman, and General Dynamics benefit directly from military escalation signals, as investors price in higher defense spending. Energy stocks gain from rising Brent crude. Technology and consumer discretionary stocks face the most pressure as oil-driven inflation fears threaten Federal Reserve rate-cut delay, extending the high-discount-rate environment that compresses growth stock valuations. For Singapore and ASEAN markets, US equity weakness from Iran escalation translates to risk-off pressure on local indices, as the Business Times' coverage signals regional investor concern.

US May CPI data is the imminent catalyst — if it shows energy inflation feeding into core prices, the Fed's rate-cut timeline shifts materially, triggering further multiple decompression in growth stocks. Watch Trump's specific retaliation announcement: a surgical airstrike represents limited escalation while broader Iranian retaliatory action including Strait of Hormuz closure risk would be a significant macro shock. The macro variable is Brent crude above $95, which signals the market has priced in extended conflict duration, while a pullback below $88 would relieve the inflation-expectations pressure currently serving as the primary equity headwind.

Synthesized from 1 source.