Micron's record HBM4 quarter ripped the memory-and-toolchain complex higher — Micron +15.7%, Applied Materials +13.4% — while SK hynix gave back its rebound in Seoul.

Micron (MU) surged 15.7% to a record $1,213.56, the basket's clear leader, after a fiscal-Q3 print that ranks among the cleanest reads yet on the HBM-memory chokepoint. Revenue hit a record $41.5B on an 84.6% gross margin, adjusted EPS of $25.11 blew past the ~$20.50 consensus, and management guided FQ4 to roughly $50B at an 86% margin. The structural news was the order book: HBM3E and HBM4 are sold out through calendar 2027 with demand reaching into 2028, and HBM4 is already in high-volume shipments to the lead accelerator customer. Micron is the smallest of the three HBM makers but the one US-listed pure-play on the most concentrated link in the AI stack, and the quarter confirmed that the memory wall — not logic — is where pricing power now sits.

SK hynix (000660.KS) was the basket's worst, falling 8.4% to KRW 2,673,000 in its latest Seoul session — a give-back of the prior session's roughly 11% snap-back rather than the US Thursday tape. The HBM leader (~55% share, two-thirds of NVIDIA's HBM4) trades as the most sentiment-driven name in the chain, and Micron's record ramp sharpens the share question: as the #3 supplier scales HBM4, the incumbent's lead narrows at the margin. The read is not a break in the HBM thesis but the volatility of the chokepoint's most-owned proxy, swinging double digits on positioning in both directions within a week.

The wafer-fab-equipment toolchain was where Micron's capex signal landed hardest. Applied Materials (AMAT +13.4%, $668) led after launching six new chipmaking systems aimed squarely at DRAM and advanced packaging — the HBM toolset — and rode the memory-capex halo; KLA (+7.6%), Lam Research (+7.2%), Onto Innovation (+6.8%) and FormFactor (+5.2%) followed, with ASML (+4.4%) and Amkor (+3.5%, advanced packaging) joining. The mega-cap buyers were the offset — Microsoft (−3.5%), Amazon (−3.1%), Meta (−2.7%) — as a soft AI-capex tape and a 6% Apple drop pulled the Nasdaq down 0.46% for a fourth straight session even as the Dow set a record. The power and cooling chokepoints stayed firmly bid: Eaton (+3.8%), Hubbell (+3.4%), Vistra (+3.0%), Vertiv (+2.9%), GE Vernova (+2.6%) and Talen (+2.7%).

The calendar is dense. Commerce'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. ASML (July 15-16) and TSMC (July 16) then open the equipment-and-foundry print wave, before SK hynix's own Q2 (July 29) gives the next HBM read after this week's Seoul wobble, and Applied Materials' fiscal Q3 (Aug 13) tests whether the memory-tool order surge is converting.