The rung nobody prices

Every chip that goes into an artificial-intelligence server has to be electrically exercised before it ships — probed at wafer level, heated, cycled and graded. That step used to be an afterthought in a fab's budget. Teradyne's management told investors on 29 July that test equipment has risen from 4% of global semiconductor capital spending in 2023 to 7% in 2025 and 8% in the first half of this year, and that the automated-test market could reach $20bn by the end of the decade against $12–14bn today. The reason is physical: a memory stack sixteen dies tall takes longer to validate than one eight tall, and warpage and thermal stress during cycling only get worse as HBM4 stacks grow.

The quarter just reported shows that arriving in revenue.

Four winners, one laggard

Advantest, the Japanese maker of memory and system-on-chip testers sold to fabless designers, foundries and test houses, grew revenue 39.3% in the June quarter at a 69.5% gross margin — an operating margin of 51.5%. On 29 July it lifted its full-year forecast to ¥1.714trn of revenue and ¥846bn of operating profit, implying about 70% operating-profit growth against a prior guide of 26%. That revenue figure sits above the ¥1.616trn analysts had modelled: the company is ahead of the sell side, not catching up to it. Management attributed the upgrade to AI test demand expanding beyond plan, with the memory business driven by high-bandwidth memory and the AI market broadening from training into inference.

Teradyne, which sells semiconductor and system test alongside the Universal Robots collaborative-robot arm, reported June-quarter revenue of $1.329bn, up 103.9%. Its Compute line grew more than 600% year on year and is now 70% of system-on-chip revenue; memory test set a record $212m with bookings running above twice billings. Operating margin went from 13.9% to 32.9%. The robotics arm that was supposed to be dead weight grew 33% to $100m. Advantest took system-on-chip tester share from 56% to 66% in calendar 2025, by one industry count; Teradyne is attacking socket by socket through dual-vendor qualification, a nine-to-twelve-month cycle whose share effects it expects to show only in 2027.

FormFactor sells probe cards — the consumable contactors that touch a wafer during test, a per-wafer stream rather than a capex approval. Revenue rose 31.9% to $258.2m and gross margin expanded 1,350 basis points to 50.7%, lifting operating income 370%. It set DRAM probe-card records on HBM4 and has qualified on Nvidia's Rubin processor. The razor-blade model cuts both ways: it guided September-quarter DRAM revenue flat as customers shift wafer mix toward conventional DDR memory.

Onto Innovation, in defect inspection and packaging lithography, grew 35.3% to $343.1m. Camtek, the Israeli inspection and metrology supplier aimed at advanced packaging, is the group's laggard on results: revenue up only 8.0%, operating income down 14.8%, margin compressed from 25.9% to 20.4%. Its order book argues the other way — more than $600m booked year to date, 80% of it advanced packaging, with September-quarter revenue guided to about 20% sequential growth.

The stocks got cheaper

The striking fact is not the run. It is that gross profit compounded faster than the share prices did. Teradyne trades at 22.42x trailing and 19.45x forward gross profit, against 25.15x trailing in mid-May and 32.04x in early May. FormFactor is at 21.76x trailing versus 34.35x in May, Camtek at 27.59x versus 34.42x. Advantest is the most expensive of the profitable four at 30.99x trailing, 23.63x forward. Gross profit is the comparable lens here because margins span 69.5% at Advantest to 40.6% at Aehr, which makes sales multiples meaningless across the group.

Aehr Test Systems, a 138-person Fremont company whose FOX platforms burn in and test whole wafers at once, has no analogue in that range: 199.5x trailing and 80.66x forward gross profit. Its fiscal year to May saw revenue fall 15.2% to $50.0m with a $14.1m operating loss, as the silicon-carbide burn-in business that once carried it collapsed. The pivot is real but sits in the order book: fourth-quarter revenue rose 40.2%, bookings hit a record $60.7m and effective backlog $100.6m against $116.5m of cash, and guidance for the current year is $130–150m. On 12 August a lead AI-processor customer placed a $22m follow-on order for systems testing nine 300mm wafers apiece. Consensus already carries $125.9m for the year — the pivot is fully marked in.

Three sessions took a fifth off

Between 17 and 19 August, Aehr fell 25.9%, FormFactor 17.0%, Camtek 15.0%, Onto 14.7%, Teradyne 14.3% and Advantest 6.2%. No company-specific catalyst was reported for any of them, and the broad semiconductor exchange-traded fund fell only 2% on the 19th. What moved was the discount rate: the 30-year Treasury yield touched 5.33% on 18 August, a 19-year high, having added more than 60 basis points in a month. Aehr's break is not the first name where the pivot failed — it is the highest-multiple name in a group being repriced on duration.

The gains were fragile in a specific way. Strip each name's two best sessions from the past 30 days and all six turn negative, Teradyne from +13.75% to −11.30%, FormFactor from +9.32% to −21.71%. Four of the six had their best day on 30 or 31 July, the sessions immediately after Teradyne and Advantest reported. A month's return delivered on two earnings reactions is a month's return that a bond move can take back.

The setup

Where it stands — The testers' results confirm rising test intensity, but every name sits well below its 52-week high after a rate-driven, cohort-wide unwind. Would confirm — Advantest's next quarter tracking toward the raised ¥1.714trn full-year revenue guide, ahead of the ¥1.616trn consensus. Would invalidate — Teradyne's flagged reversion of test to 6–7% of semiconductor capex in 2027, or memory book-to-bill falling below 1. Watch next — Aehr's fiscal first-quarter report, the first test of whether $100.6m of backlog converts toward the $130–150m guide. Valuation — Group forward price-to-gross-profit of 19.0x to 25.9x, down from 34x in May; Aehr at 80.66x forward, 199.5x trailing.