Q3 opened with a chip-led rout — the memory chokepoint cracked (SK hynix −14.6% in Seoul, Micron −10.6%, CoreWeave −13.9%) — while the silicon-wafer squeeze lifted SUMCO +13.3% and Meta jumped 8.8% on an AI-cloud plan.

SUMCO (SUOPY) led the compute basket in its own session, the US line up 13.3% to $57.50 as its Tokyo listing ripped roughly 17% — a divergence from a collapsing semiconductor tape that is itself the session's tell. SUMCO sits on the substrates-and-materials chokepoint: it is one of two suppliers of the 300mm silicon wafers every leading-edge accelerator and memory die is printed on, and the stock is being repriced on an AI-driven wafer supply squeeze, with Nomura among the brokers lifting demand forecasts into long-term contract renewals. Tight wafer supply is pricing power for the wafer maker — and, crucially, the DRAM-pricing controversy hammering the memory names does not touch the substrate underneath them. On a day the complex broke, the chokepoint furthest upstream went the other way.

The break was in memory. SK hynix (000660.KS) fell 14.6% in Seoul's latest session as Wall Street's rout spilled into Asia, and the HBM-memory chokepoint was the epicenter on the US tape too: Micron (MU) −10.6% to $1,032.28, and CoreWeave (CRWV) −13.9% to $85.69 on the accelerator-capacity node. A US class-action alleging the big three memory makers restricted conventional DRAM output to inflate prices — while shifting capacity to high-bandwidth memory — gave a specific catalyst to a market already reassessing an overstretched AI-hardware trade. The process-control and litho toolchain followed: KLA (KLAC) −11.8% to $266.19, Applied Materials (AMAT) −10.0%, Lam (LRCX) −9.7%, ASML (ASML) −7.4%, TSMC (TSM) −7.0%.

The one big up-move on the US tape was the session's pivot. Meta (META) jumped 8.8% to $612.91 on a Bloomberg report that it is building a cloud business to rent out excess AI compute — and that same report is what broke CoreWeave, because a hyperscaler renting raw compute is the neocloud model, and the read was customer-concentration risk for the specialists. The other hyperscalers extended their rebound (Microsoft +3.0%, Amazon +1.4%, Alphabet +1.1%), but the picks-and-shovels chokepoints sold off across the board: optical interconnect (Marvell −8.7%), advanced packaging (Amkor −7.2%, Onto −7.2%), cooling (Vertiv −7.0% to $311.42), and the data-center-power complex again (Talen −6.1%, Constellation −4.8%). Only the materials names firmed alongside SUMCO — Ajinomoto (AJNMY) +4.0% on ABF substrate, Shin-Etsu (SHECY) +2.3%.

The calendar turns immediately policy-heavy. Commerce's Section 232 data-center-semiconductor report to the President is due around now, and PJM's 2028/2029 Base Residual Auction closes July 7 — a direct read on the data-center power premium that Talen and Constellation trade on. The first hard fundamental tests then arrive with ASML and TSMC's Q2 prints in mid-July, the first checks on whether leading-edge tool and foundry demand matches the AI narrative, followed by Micron's fiscal Q3 and first full HBM4-ramp guide, then AMD, NVIDIA, and Vertiv.