Credo surged 11.3% on a blowout quarter and US semis led the tape, but Seoul's Tuesday circuit-breaker crash sent SK hynix down 12.5% in the HBM chokepoint.

Credo Technology (CRDO) rose 11.3% to $302.52, the cluster's standout, on a genuine company catalyst. Fiscal-Q4 revenue hit $437M, up 157% year over year, with non-GAAP EPS of $1.16 against the $0.98 consensus, and management guided Q1 FY27 to $465–475M; Needham, Roth, BofA, Jefferies, Mizuho, Susquehanna and JPMorgan all lifted targets, and the DustPhotonics acquisition gives Credo a vertically integrated 800G–3.2T silicon-photonics stack. Credo sits squarely on the optical-interconnect chokepoint — the active electrical and optical cabling that moves bits between accelerators once copper runs out of reach — so a triple-digit print there reads as the bandwidth strait widening, not just a single name re-rating.

The laggard came from across the Pacific, a session later. In Seoul's Tuesday cash session, SK hynix (000660.KS) fell 12.5% to KRW 2,555,000 as the KOSPI triggered circuit breakers twice and closed down roughly 10%. The trigger was a structural unwind — regulatory scrutiny of leveraged semiconductor-linked products and forced liquidation of those positions, layered on AI-valuation jitters after leadership departures at Google — that hit the memory complex hardest, with Samsung also off ~12% and Kioxia down more than 15%. SK hynix is the HBM-memory chokepoint, ~60% of high-bandwidth-memory share and the gating supplier of NVIDIA's HBM4; a one-session air-pocket of that size is a reminder that the most concentrated link in the AI stack is also the most reflexive.

The US Monday tape was the mirror image: semis and the physical buildout rallied while the hyperscalers sold off. Micron (MU +6.8%, $1,211.38) ran into Wednesday's FQ3 print, Fabrinet (FN +7.6%), ASE (ASX +7.5%), Vertiv (VRT +7.5%), Lumentum (LITE +5.2%), Lam (LRCX +5.3%) and Intel (INTC +5.2%) led, and the power chokepoint that gates the megawatts joined in (Quanta PWR +5.4%). Against that, the customers funding the capex fell — Alphabet (GOOGL −5.0%), Amazon (AMZN −4.7%), Microsoft (MSFT −3.2%), Broadcom (AVGO −4.7%) and CoreWeave (CRWV −5.6%) — a split tape that prices the picks-and-shovels over the platforms.

The catalysts come fast. Micron's FQ3 lands June 24 — the first full HBM4-ramp quarter and the cleanest read on the memory chokepoint after Seoul's wobble. The Commerce Department's Section 232 data-center-semiconductor report to the President is due around July 1, a latent onshoring catalyst, and PJM's 2028/2029 capacity auction closes July 7, a direct read on the data-center power premium. Then ASML (July 15) and TSMC (July 16) open the equipment-and-foundry print wave, with SK hynix's own Q2 on July 29 the next scheduled look at whether the HBM "sold-out" narrative survived the tape.