Lam Research (NASDAQ: LRCX) ripped about 18% higher on Thursday, to around $296 — as reported by TradingKey and StockStory — one of the biggest single-session moves in the S&P 500. The trigger wasn't the quarter it just closed. It was the one it just guided to.

The quarter itself was strong: fiscal Q4 (ended June) revenue of $6.72 billion, up 30% year-on-year and about 15% sequentially, with adjusted EPS of $1.82 versus the ~$1.72 the Street wanted (Seeking Alpha). But an earnings beat rarely moves a chip giant 18%. What did it was the September-quarter guide: ~$8.1 billion in revenue (±$400M) and $2.15 EPS — roughly $1 billion above the ~$7.1B analysts had penciled in. Guidance a full billion ahead of consensus is the number that repriced the stock.

Why the guide is the whole story

Lam sells the etch and deposition machines that carve and layer memory chips. Management said NAND revenue roughly doubled sequentially, driven by AI demand for flash storage and the upgrade to 200-plus-layer architectures — and it lifted its 2026 wafer-fab-equipment (WFE) outlook to the "low $150 billion" range, up from about $140 billion (Seeking Alpha). That's a direct rebuttal of the "AI memory glut" scare that knocked chip stocks lower earlier this week.

The ripple: Lam raising the size of the whole WFE market is a read-through for its two big equipment peers, Applied Materials (AMAT) and KLA (KLAC) — they sell into the same fabs, so a ~$10B bigger 2026 equipment pie lifts their order books too. AMAT fell about 8% on Wednesday on that same glut fear; Lam's guide is the counter-evidence, and AMAT's own quarter is the next test of whether it sticks.

The risk that flips it: the $8.1B guide assumes memory makers — Micron, SK Hynix, Samsung — actually place the tool orders. If any of them trims capex, the WFE-to-$150B call cracks. Watch whether the September quarter lands near that $8.1B (±$400M) mark, and whether AMAT echoes the WFE-up story. And note the stock is still about 31% below its June high of $433 — reclaiming that is the bull target; losing today's ~$296 would be the first sign the pop is fading.

As of Thu 30 Jul 2026, 3:02 PM ET. Sources: Seeking Alpha, TradingKey. For discussion and education only — not investment advice. Verify before acting.