Lam Research pops 18%, best day since 1999 on AI demand

The number that stopped traders on Thursday was not the earnings beat itself, but the September-quarter guide. Lam Research told the market to expect roughly $8.1 billion in revenue and $2.15 in EPS for the current quarter, well ahead of where the sell side was modelling, and the stock ripped 18% in what CNBC reported was its best day since 1999.

The backing print was already strong. Fiscal Q4 revenue came in at a record $6.72 billion, up 30% year over year, adjusted EPS was $1.82 against a $1.69 consensus, and full-year fiscal 2026 revenue landed at $23.2 billion. Gross margin hit 52%, which the company called its highest quarterly gross margin in twenty years, and operating margin reached 38.4%. CEO Tim Archer framed it, per the Investing.com transcript, as AI-driven demand reshaping the industry, with NAND revenue reportedly doubling from the prior quarter.

Why the reaction spread so wide is the more interesting bit. Micron closed up 18%, Sandisk 26%, AMD 13% and Applied Materials 15% on the same session. Earlier in the week the sector had shed more than a trillion dollars of market value on fears the AI capex cycle was topping out, and Samsung had reportedly warned that the memory shortage could run into 2028. Lam's guide effectively told that bear case to sit down: the equipment order book is not flattening, it is accelerating, and memory suppliers are the ones with pricing power.

The honest caveat is that one quarter's guide from one vendor is not a cycle. Guides can miss, and equipment revenue is famously lumpy because it tracks a handful of hyperscaler and foundry customers. What the reporting does not give you is the customer concentration behind that $8.1 billion, the China share of the full-year number, or how much of the margin expansion is durable versus a supply-tightness peak.

For now the read is straightforward. If you are an allocator, the trade is still long the picks and shovels of AI compute, and long the memory suppliers with the leverage to price into a multi-year crunch. If you are a buyer of that capacity, the message is less friendly: the next round of NAND and DRAM contracts is going to be negotiated from a position of weakness.