Contract manufacturers have historically been the least capital-hungry link in the electronics chain: they buy components, assemble to a customer's design at low-single-digit margins, and hand back cash. That arrangement is being renegotiated in public. Celestica, a Toronto-based builder of routers, switches, interconnects and custom server racks for hyperscale cloud operators, announced a $3 billion equity offering on 5 August to fund investments supporting what it called unprecedented multi-year demand. The 9,677,419 shares were priced at $310 against a prior close of $362.76 — about 8.3% dilution on roughly 116 million diluted shares, before a 15% underwriter option — and the stock fell 14.8% the following session, the largest single-day move in the group this year.

The raise is a symptom, not an outlier. Celestica's capital spending has gone from 1.1% of revenue a year ago to 5.6% last quarter, with $1bn budgeted this year and a $1.5bn placeholder for next. Flex cut its free-cash-flow conversion guidance to about 40% from 60% on $1.5–1.6bn of capex. Celestica, Sanmina and Benchmark have all paused or deprioritised buybacks in favour of capacity. The assembly layer is becoming an asset-heavy business while the market is asking harder questions about who finances the artificial-intelligence buildout.

The tape moved before the numbers did

All six names — not four — stepped down from their strongest uptrend classification inside 22 trading days, sequenced by AI exposure: Celestica on 30 June, Sanmina 8 July, Jabil 14 July, Flex 17 July, Plexus 21 July, Benchmark 22 July. Every one of those dates precedes the company's own results. That is a sector de-rating, and it coincides with a credit event, not a demand event: tech bonds sold off on 23 July on fears about the scale of the debt-funded AI boom, hyperscalers and Nvidia issued $225bn of bonds by midyear, up roughly 974%, with Amazon paying 18–21 basis points extra on a $25bn deal, and loan investors began demanding better terms on AI credit in the week to 1 August. Drawdowns from June highs are far deeper than the group's 2.9% monthly average suggests: Celestica −32.8%, Sanmina −28.2%, Flex −24.9%.

The businesses went the other way

Celestica's June quarter revenue rose 62.4% to $4.699bn — a fourth straight quarter of acceleration — with operating margin at 9.75% against 9.42%, and it raised full-year guidance to $20.5bn and $11.30 of earnings per share while disclosing 2027 rack programmes for OpenAI and interconnect work for AMD.

Flex, the Singapore-founded manufacturer that also makes switchgear, busway and modular power systems for data halls, grew revenue 20.6% to $7.928bn with gross margin up from 8.70% to 9.42%; its Cloud & Power Infrastructure unit grew 35% to $2.2bn at a 9.7% operating margin and is guided to 65–75% growth this year. Its supposedly soft legacy book grew 12% with margins up 130 basis points. The shares still fell about 9% on the print.

Sanmina, the San Jose maker of backplanes, enclosures and printed circuit boards now carrying the acquired ZT Systems server business, grew revenue 69.7% to $3.464bn with operating margin up 173 basis points — the best expansion in the group — as cloud and AI reached 62% of revenue. It beat on both lines but guided the current quarter about 2% below consensus on legacy programme timing.

Jabil, the Florida manufacturer serving networking, storage, healthcare and semiconductor equipment customers, is the one decelerator: revenue growth slowed to 11.8% from 23.1% and operating margin slipped six basis points, though it lifted AI-related revenue guidance to about $13.6bn, up 50%. It last reported on 17 June, so it has had no late-July reset.

The two names assumed to have no AI exposure do. Benchmark Electronics, the Arizona builder of aerospace, defence, medical and semiconductor-equipment hardware, grew its advanced computing unit 71% and guided to a record $3.0bn year. Plexus, the Wisconsin manufacturer of medical, industrial and defence electronics, disclosed roughly $0.5bn of data-centre funnel and a record $4.5bn total funnel. Both are the least damaged on the tape — and, with Jabil, are what masks the declines elsewhere.

Verdict A — does the business explain the move? CONTRADICTS. Five of six accelerated, five of six expanded operating margins, and all six raised guidance into the selloff. Demand upstream also rose: the four largest cloud buyers lifted 2026 capital spending plans to roughly $725bn, up 77% — and were sold for doing so.

Verdict B — does valuation justify it? INCONCLUSIVE, and it splits. Celestica trades at 32.7x trailing and 27.9x forward against roughly 40x forward in this Desk's May reading; Flex at 46.9x trailing but 25.8x forward, versus 59x trailing in May; Jabil 42.1x/26.8x with a 4.2% free-cash-flow yield. Multiples compressed while guidance rose, so the last leg was earnings. Sanmina is the cheapest at 16.8x forward, 17.1x enterprise-value-to-EBITDA and a 9.5% free-cash-flow yield on consensus earnings growth of 103%. Plexus is the opposite: 31.5x forward, 29.0x EV/EBITDA, a 0.9% cash yield, 19.5% expected growth and the only contracting reported margins in the group. Benchmark sits at 27.8x forward with growth slowing to 13% next year.

The unresolved question is not orders. It is that Celestica's top three customers are about 65% of revenue, up from 51%, and it just funded their capacity with discounted equity.

The setup

Where it stands — Six assemblers beat and raised into a July de-rating; Celestica then diluted holders 8.3% to fund capacity.

Would confirm — Flex's Cloud & Power segment printing 45–55% growth next quarter and Celestica holding $20.5bn full-year revenue.

Would invalidate — Any of the six cutting AI-segment guidance, or a second equity raise in the group at a discount.

Watch next — Jabil's fiscal fourth-quarter results in late September, the first fresh guidance since 17 June.

Valuation — Group forward earnings multiples run 16.8x (Sanmina) to 31.5x (Plexus), against roughly 28–59x trailing readings in May.