Daily brief

Every weekday morning an AI co-pilot reads the overnight tape across the book, cross-references the catalyst calendar, and writes what moved and why.

• 2026-10-27A broadening optical-interconnect rally carried the AI-infrastructure complex, led by Lumentum, while advanced-packaging name Amkor was the one rung that broke lower.
• 2026-10-26The AI-infrastructure complex steadied on Friday after Thursday's rout, with semicap, memory and foundry rungs firming, while optical-interconnect name Credo kept bleeding and the datacenter-power trade stayed soft.
• 2026-10-23A full-stack AI-infrastructure selloff hit every US rung of the compute basket — semicap, optics, packaging and datacenter power all down double digits — while the memory strait held, with SK hynix the only gainer in its own Seoul session.
• 2026-10-22Optical-interconnect name Credo led the AI-compute basket on analyst bullishness as the broader semi tape made records, while SK hynix fell in its own Seoul session on profit-taking.
• 2026-10-21SK hynix led on a report Nvidia wants custom-HBM base dies as the semiconductor index gave back part of Monday's rebound, with wafer supplier SUMCO the laggard.
• 2026-10-20The AI-buildout stack rebounded as the semiconductor index ended an eight-session skid, with electrical-steel supplier Cleveland-Cliffs the standout on a Q3 beat.
• 2026-10-19The AI-buildout stack sold off as one correlated block on its ninth straight semiconductor down-session, with the leveraged neocloud rung the clear casualty and no real leader.
• 2026-10-16CoreWeave bounced 5.9% off Wednesday's rout but the AI-buildout rungs stayed soft, with the substrate chokepoint the worst hit as Japanese chip names sold off hard.
• 2026-10-15A hot CPI print triggered the worst AI-complex selloff since July — CoreWeave -15.5%, the optical and HBM rungs down double digits, the power rung off 5-7% — with no equity in the basket green but a crossover fund.
• 2026-10-14Applied Materials -6.7% led a wafer-fab-equipment selloff after its investor day skipped a spending forecast, while the power rung took the AI bid — Vistra +2.7%, Meta +2.6%.
• 2026-10-13A China-memory scare broke the AI supply rungs — optics led the fall, Lumentum -9.8%, after CXMT flagged a denser DRAM cell — while the hyperscaler buyers held, Meta +3.4%.
• 2026-10-12Electrical steel topped an AI-capex relief bounce — Cleveland-Cliffs +6.5% on a Wells Fargo upgrade and a grid-steel expansion — as the power and optics rungs rebounded; SK hynix lagged, -4.5% in Monday's Seoul session.
• 2026-10-09The source of Thursday's selloff hit compute hardest — SoftBank off 9.9% and the AI-optics complex down double digits, with Applied Optoelectronics the laggard at -13.6%; only cooling and power held.
• 2026-10-08Memory and power stayed bid while the advanced-packaging complex sold off — Micron up 4.1% to a record handle, BE Semiconductor off 8.3% as the day's funding source.
• 2026-10-07Merchant-nuclear and power names ripped on Google's 20-year, 890 MW reactor-uprate deal with Constellation, while the wafer-fab-equipment complex sold off as the session's funding source.
• 2026-10-06Electrical steel led on tariff tailwinds while Schneider's ADR cratered on its record $22.6B cash bid for PTC — the cooling-thermal choke paying up for software.
• 2026-10-05The optical-interconnect and advanced-packaging rungs ran again on a dovish-Fed tape as Modine fell on a spin-off completion.
• 2026-10-02An optical-interconnect melt-up led by Coherent's PhotonLink lifted the whole datacenter-optics rung as life-science materials lagged.
• 2026-10-01FormFactor led the back-end test rung on an Nvidia probe-card win as money rotated out of the data-center power names.
• 2026-09-30A broad semicap and advanced-packaging rally reversed Monday's AI-hardware selloff, with back-end inspection names out front.
• 2026-09-29An AI-hardware selloff — amplified by OpenAI pausing training on some advanced models — hit accelerators, interconnect, and cooling, while Nvidia's buyback kept the accelerator rung green.
• 2026-09-28Credo's earnings blowout lit up the AI-interconnect rung on Friday, while SK hynix's Monday Seoul reopening dropped 5% on foreign selling and a Solidigm-listing overhang.
• 2026-09-25Meta's Muse rally pulled the demand rung higher while SoftBank slid on OpenAI-timing doubts and a record junk-bond sale.
• 2026-09-24A 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.
• 2026-09-23A memory-capex bid lifted the semiconductor-equipment complex — FormFactor, Entegris and Micron led — as Coherent gave back its data-center-optics gains.
• 2026-09-22Meta's Muse AI agent sparked a broad chip rally that sent Intel up 12% on foundry optimism, while electrical-steel name Cleveland-Cliffs bucked the tape lower.
• 2026-09-21The tools-and-optics layer ripped on an oversold bounce led by Applied Optoelectronics, while power names and SoftBank gave back.
• 2026-09-18The memory-and-foundry strait ripped on Intel's SK hynix tie-up rumor, while CoreWeave fell on a $3B convertible-and-equity raise.
• 2026-09-17The optical-interconnect strait ripped on fresh AI-optics coverage, led by Lumentum, while the platform megacaps drifted lower.
• 2026-09-16SoftBank staged a violent reversal on a concrete SB Energy IPO filing, undoing most of Monday's plunge, while the power-and-memory core traded on rates.