A memory-capex bid lifted the semiconductor-equipment complex — FormFactor, Entegris and Micron led — as Coherent gave back its data-center-optics gains.

FormFactor (FORM) led the vertical, up 5.6% to $126.01, just ahead of Entegris (ENTG) +5.6% to $151.11, as the wafer-fabrication-equipment and materials rung rallied on memory capital spending. With 2026 WFE outlays projected to a record ~$135B — driven by HBM, advanced DRAM and enterprise NAND for AI infrastructure — the tools-and-materials layer is the fabrication chokepoint that gates how fast AI-compute supply can actually be built. Tuesday's tape rotated money into that upstream rung after Monday's accelerator-led melt-up.

Coherent (COHR) was the laggard, down 3.5% to $310.39, on profit-taking in data-center photonics one day after its PhotonLink co-packaged-optics launch; Applied Optoelectronics (AAOI) softened alongside at −1.5% to $107.00. Optical interconnect is the bandwidth chokepoint between accelerators, so the pullback is a give-back of recent strength rather than a demand signal — the group had run hard into the launch.

The engine underneath was memory. Micron (MU) rose 5.0% to $1,096.16 heading into its Sept 30 fiscal-Q4 report, with DRAM/NAND pricing tight and HBM reportedly sold out through 2026; advanced-packaging house Amkor (AMKR) +4.6% to $54.59, Lam Research (LRCX) +2.9% to $310.96, KLA (KLAC) +2.4%, Applied Materials (AMAT) +1.8%, and TSMC's ADR (TSM) +1.5% rounded out the equipment-and-foundry bid. The accelerators cooled after Monday: NVIDIA (NVDA) +0.7% to $228.87, AMD (AMD) +1.3%, Intel (INTC) +1.7%, and Meta (META) −0.6% to $736.60, giving back a sliver of its Muse-driven surge. The power rung eased — Talen (TLN) −1.8% to $294.54, Vistra (VST) −0.3%, Constellation (CEG) +0.5% — as the day's leadership shifted from energy to silicon tools.

The catalysts ahead are earnings- and conference-driven. Micron's fiscal-Q4 print on Sept 30 is the memory-pricing tell that either validates or punctures the equipment rally. Ecolab's ~$4.75B acquisition of liquid-cooling maker CoolIT is expected to close in Q3 — a read on the thermal chokepoint as racks outgrow air. The OCP Global Summit (Oct 12–15) and SEMICON West (Oct 13–15) 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 Monday's foundry optimism.