Quantinuum fell 7.0% as the pure-play quantum names extended Monday's dilution-driven selloff, while the compute-adjacent silicon — AMD +1.9% — held against a sharp WFE-led equipment slide.

Advanced Micro Devices (AMD) led the quantum basket Tuesday, up 1.9% to $605.53, with IBM +1.7% to $230.78 and Intel +1.4% to $102.81 — the large-cap compute names that anchor the sector's classical-control and cryo-adjacent supply, holding firm as the broad chip tape clawed back a morning loss. But the leadership was defensive in character: the gains sat in the diversified semiconductor majors, not in the fault-tolerant hardware names that define the vertical. Underneath them, the pure-play quantum complex had its second rough session in a row.

Quantinuum (QNT) was the laggard, down 7.0% to $36.76 — now roughly 39% below its June 2026 IPO price of $60, the first traditional listing of a full-stack quantum company. The selling was sector-wide and traces to Monday's catalyst: IonQ's up-to-$1.3B all-stock acquisition of cybersecurity firm Elisity, a deal whose equity consideration reignited dilution fears across the group. That overhang carried into Tuesday — IonQ (IONQ) -4.2% to $34.73, Rigetti (RGTI) -3.5% to $12.78, D-Wave (QBTS) -2.6% to $13.38, Infleqtion (INFQ) -2.7% to $10.10 — with the richest-valued recent IPO, Quantinuum, repricing hardest. Arqit (ARQQ) was a rare exception at +1.1% to $16.84.

The deeper damage was in the enabling-technology rungs, where quantum shares the supply chain with the wider semiconductor-equipment complex. Applied Materials (AMAT) fell 6.7% to $464.24 after its investor day passed without an industry wafer-fab-equipment spending forecast, triggering profit-taking after an ~80% year-to-date run; the read-through hit the toolmakers and metrology names quantum depends on — GlobalFoundries (GFS) -3.4% to $46.70, Keysight (KEYS) -2.0% to $370.22, FormFactor (FORM) -1.7% to $128.09. The isotope and enrichment rung, which underwrites qubit-grade materials, was weak too: ASP Isotopes (ASPI) -6.6% to $2.28 and Silex (SILXY) -6.6% to $12.98. Photonics component maker Coherent (COHR) bucked it, +0.7% to $289.98.

The calendar ahead is dominated by the one government decision the hardware names most watch: DARPA's Quantum Benchmarking Initiative, whose Stage B concludes around November 6 with Stage B-to-Stage C down-select decisions clustering through late November — the funding signal that will separate the credible roadmaps from the rest. Beyond that, Q2B26 Chicago (December 8-10) is the industry's year-end venue for utility-scale claims, and Gooch & Housego's FY2026 results on December 8 offer a read on the photonics-component rung. Until the DARPA verdict lands, the pure-plays remain a sentiment trade dominated by dilution math, not milestones.