The 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.

The leader was Cleveland-Cliffs (CLF), up 16.3% to $14.10 on the power-and-grid chokepoint, where its grain-oriented electrical steel feeds the transformers the datacenter buildout is starved for. The move was a genuine earnings event, not a tape rebound: third-quarter adjusted EBITDA of $612 million more than doubled the prior quarter's $286 million, adjusted EPS of $0.28 beat the roughly $0.24 consensus, and management guided fourth-quarter adjusted EBITDA near $715 million and raised its 2027 target above $4 billion — its strongest quarterly result in three years. It capped a session where the broader complex rebounded: the Philadelphia Semiconductor Index rose 1.6%, ending an eight-session losing streak, its longest in 18 years.

The laggard was SK hynix (000660.KS), down 4.2% to ₩1,223,000 on its Seoul line's most recent session — the HBM-and-memory-bandwidth chokepoint's anchor pulling back after leading the complex for months. The decline reflects its home-market tape rather than the US rebound, which did not reach Korea in the same session; the structural HBM-supply thesis is intact, and the US-listed memory rung in fact rallied, with Micron (MU) +3.0% to $904.90.

The rebound was broad across the hardware rungs. Lithography and deposition led — Lam Research (LRCX) +3.1% to $272.20, Entegris (ENTG) +4.2% to $144.52 on the materials rung, FormFactor (FORM) +4.9% to $110.16 on test. Optical-interconnect snapped back: Applied Optoelectronics (AAOI) +3.5% to $78.20, Arista (ANET) +3.4% to $182.95, Marvell (MRVL) +4.1% to $237.09. The accelerator and foundry anchors joined — Amazon (AMZN) +5.0% to $262.45, Intel (INTC) +2.4% to $92.03 on a JPMorgan upgrade, TSMC's ADR (TSM) +1.8% to $420.22, Broadcom (AVGO) +1.8% to $334.59, NVIDIA (NVDA) +1.4% to $217.09. The leveraged-neocloud rung stabilized: CoreWeave (CRWV) was roughly flat, −0.4% to $61.12, after Friday's 11.9% rout. The power rung was the session's soft spot — Constellation (CEG) −3.0% to $263.19, Vistra (VST) −1.5% to $149.70, GE Vernova (GEV) −1.4% to $908.44, Talen (TLN) −1.0% to $351.22.

The near calendar is thin, which leaves the macro and the AI-financing question in control. The next dated milestone with structural weight is the year-end window for Intel's 14A external-customer decision — the domestic leading-edge validation the foundry rung is waiting on — with Ibiden's Gama/Ono AI-substrate ramp running through FY2027 behind it. Whether Monday's bounce holds depends on the rate picture and the neocloud-funding debate, not the chip-demand signal, which never wavered.