A second day of AI-led selling hit the accelerator and optics complex — Alphabet, Broadcom and Micron fell — while FormFactor's test-and-HBM rung led the survivors.

FormFactor (FORM) led the vertical, up 4.2% to $131.26, extending Tuesday's memory-capex bid as the wafer-test and probe-card rung outran a falling tape. FormFactor reported record DRAM probe-card revenue on rising HBM demand, and its probe cards are the characterization chokepoint that gates how fast advanced memory can be tested and shipped into AI infrastructure. On a session when the accelerators and optics sold off, money stayed with the upstream tools-and-test layer that gets paid whether the winning silicon is NVIDIA's, AMD's or a hyperscaler's own.

Applied Optoelectronics (AAOI) was the laggard, down 5.6% to $101.06, extending its slide on financing rather than demand: a ~$600M at-the-market equity program has left the stock hostage to dilution and execution risk even as datacenter revenue runs at record levels on first-volume 800G shipments. Optical interconnect is the bandwidth chokepoint between accelerators, so AAOI's move is a balance-sheet story, not a signal that the interconnect demand curve has bent.

The session was a second straight day of rotation out of AI-levered tech — the Nasdaq fell while the Dow rose — with the selling widening from the megacaps that ran on Meta's Muse launch to the names most exposed to AI disruption. Alphabet (GOOGL) dropped 3.8% to $337.83 into its earnings window; Broadcom (AVGO) −2.6% to $354.99, Amazon (AMZN) −2.2%, NVIDIA (NVDA) −1.5% to $225.51 and AMD −1.5% led the accelerator-and-networking rung lower, while Meta (META) +1.0% to $744.10 and Microsoft (MSFT) +0.5% held. Memory eased into its print — Micron (MU) −2.2% to $1,071.88 — and the equipment names softened with Lam (LRCX) −1.2% and Amkor (AMKR) −2.3%. The power rung firmed as capital rotated: Talen (TLN) +2.0% to $300.34 and Constellation (CEG) +0.2%, against Vistra (VST) −1.7%.

The catalysts ahead are earnings- and conference-driven. Micron's fiscal-Q4 report on Sept 30 is the memory-pricing tell that either validates or punctures the equipment rally that led today. Ecolab's ~$4.75B acquisition of liquid-cooling maker CoolIT is expected to close this quarter — a read on the thermal chokepoint as racks outgrow air. The OCP Global Summit (Oct 12–15, San Jose) and SEMICON West (Oct 13–15, San Francisco) are the next hardware and equipment showcases, the OpenAI IPO listing window opens in Q4, and Intel's 14A external-customer decision window opens at year-end — the signal that would extend the domestic-foundry optimism the selloff has, for now, set aside.