Sterling Infrastructure, the Woodlands, Texas contractor that grades the ground and pours the foundations under new data centers, told investors on 4 August that signed backlog had reached $4.3bn, more than double a year earlier. It raised full-year guidance to revenue of $4.00-4.15bn and adjusted earnings of $19.70-20.30 a share. The shares fell 9.4% that day and roughly 14% intraday, investors focusing on the margin implied by the added revenue.

By then most of the damage was already done. Sterling fell 25% over four sessions into 28 July, before it reported anything. That week belonged to the customers, not the builders: Alphabet's 23 July capital-spending raise sent its own shares down 7% and set up Amazon, Meta and Microsoft to meet skeptical investors, with Meta dropping nearly 10% after guiding 2026 capital spending to $125-145bn on costlier memory, chips and data-center components. On 29 July, chip stocks shed more than $1 trillion of market value. The contractors were downstream of that.

Proximity to the pad, not distance from it

Which names fell inverts the intuitive reading. Over the past month Sterling is down 21.1%, MasTec 19.7% and Argan — the gas-fired power plant builder — 17.3%. Dycom, the West Palm Beach specialty contractor that places and splices fiber for carriers and cable operators, is down 3.2%. Quanta Services is up 3.2%. Widen the frame and the pattern holds: EMCOR gained 5.3% over the same month and IES Holdings 7.1%. This was not a construction selloff. It was a selloff in the companies whose order books read most directly as a bet on new campuses being started.

Only one of the falls has a disclosed cause inside the business, and it is not a data-center one. MasTec, the Coral Gables infrastructure builder, lost 18.9% in a single session on 31 July after lowering its communications outlook on a wireless slowdown and wireline projects deferred into 2027, with a raised earnings midpoint of $9.30 that still sat below where analysts had been. Its 18-month backlog hit a record $21.4bn, clean energy up 58%.

Dycom was supposed to be the control at the wrong end of this trade — a telecom builder with no compute load to serve. It is instead the most resilient member and the cheapest, at 9.6x trailing and 7.9x forward gross profit, 13.4x trailing enterprise value to EBITDA. Its last report, on 27 May, showed revenue up 56.1%, backlog of $11.9bn and raised fiscal 2027 guidance of $7.38-7.65bn; the honest caveat is that only 24.7% of that growth was organic and gross margin compressed about a point, to 14.0%. Long-haul fiber between campuses is compute infrastructure too.

What Sterling actually conceded

Sterling's second quarter was not ambiguous. Revenue rose 90.1% to $1.168bn, the fourth consecutive quarter of acceleration. Gross margin widened to 24.18% from 23.29%, and operating income grew 113.8% — faster than revenue, which is what operating leverage looks like. More than 92% of E-Infrastructure backlog is mission-critical work: data centers, semiconductor plants and manufacturing.

The concession is mix. Sterling's acquired electrical business is growing 140% at roughly 12% operating margins, against site development in the high-20s, pulling segment guidance toward the mid-20s. Management also flagged softer third-quarter award timing and warned backlog could fall sequentially. That is a genuine reason to pay less per dollar of revenue — but the market has repriced the whole franchise, not the increment. Price per dollar of trailing gross profit has gone from 43.2x in mid-May to 19.6x, with 16.6x forward; trailing earnings are 36.9x against 78x earlier in the year. Consensus models $4.06bn of 2026 revenue and $19.78 of earnings — estimates that rose with the results.

Sterling's durable advantage is incumbency: once it wins the first phase on a campus it negotiates the next ones directly rather than re-bidding, and it is now selling electrical work alongside site work on three or four projects, up from none a year ago. The binding constraint is electricians, not orders.

Quanta is the different animal here. The Houston contractor reported record backlog of $53.4bn, up 50%, with remaining performance obligations of $33.6bn, revenue up 41.1% and gross margin at 16.17% against 13.21%. But technology and large-load work is 15-20% of revenue — four-fifths of that backlog is transmission, renewables and pipelines. It self-performs 80-85% of its work and spends $250m a year training craft against a four-year journeyman pipeline. It also carries the group's steepest absolute price: 72.4x trailing earnings, 33.7x trailing EV/EBITDA.

The channel that matters next

The transmission from AI sentiment to contractor order books runs through owners' financing costs, and it is tightening. Morgan Stanley notes investment-grade data-center secured bonds have widened 40 basis points since mid-June and high-yield equivalents 120 basis points, against $360bn of global fixed-income supply this year. That is a cost of capital for the people who sign the pads, and it shows up in awards long before it shows up in revenue.

A second leg down hit every name in the week to 21 August — Sterling off 14.6%, Argan 14.5%, MasTec 11.9%, Quanta 8.8% — and Sterling's 50-day average crossed below its 200-day on 20 August, ending an uptrend that had run since spring. Dycom's crossed on 19 August despite the shallowest decline of the five. Twelve-month gains are dented, not erased: Argan is still up 136.1%, Sterling 86.4%, Quanta 71.5%.

The setup

Where it stands — Sterling's backlog and guidance rose through a selloff that halved what buyers pay per dollar of its gross profit. Would confirm — Third-quarter E-Infrastructure margin holding at or above 24% with combined backlog flat or higher. Would invalidate — A sequential backlog decline that management attributes to cancelled or deferred campuses rather than award timing. Watch next — Dycom's fiscal second-quarter report in late August, its first disclosure since 27 May. Valuation — Sterling at 19.6x trailing and 16.6x forward gross profit, against 43.2x in mid-May; Quanta 20.4x, Dycom 9.6x.