US Stock Market Today: S&P 500, Nasdaq Plunge Up To 1% On Tech Selloff; Micron Erases AI Gains

US equities sold off broadly on Tuesday, with the S&P 500 and Nasdaq each falling close to 1%, led by weakness in the technology sector. Micron Technology (MU) was a notable decliner, giving back a chunk of the AI-driven rally it had accumulated over recent months. The macro backdrop — rate uncertainty and stretched AI valuations — appeared to be the primary driver rather than any company-specific negative.

Micron's own fundamental picture remains strong: FY2025 revenues reached $37.4B, up nearly 49% year-over-year, with gross margins at 39.8% and diluted EPS of $7.59. The HBM (High Bandwidth Memory) cycle underpinning AI infrastructure build-outs is still intact, and MU remains one of the most direct ways to play that theme in public markets.

The tension here is whether this selloff is a healthy reset in a structurally strong AI memory upcycle, or the beginning of a more meaningful de-rating as the market questions the duration and magnitude of AI capex. MU is still trading at a multiple that prices in continued HBM demand growth, so any signal of softening from hyperscalers could accelerate the pullback.

What to watch: hyperscaler capex commentary in upcoming earnings calls, DRAM spot price trends, and whether MU holds key technical support levels. A bounce from here would reinforce the bull case that the AI memory cycle has legs; a break lower would suggest the market is pricing in a sharper-than-expected inventory correction.