EMCOR Group, the electrical and mechanical contractor that installs power distribution, chilled-water piping, clean-room ventilation and low-voltage cabling inside a data hall, told investors on 30 July that its order book had reached a record $17.14bn — up from $11.91bn a year earlier, with the largest growth in network and communications. It also told them something less comfortable. Only about three-quarters of that book will convert to revenue within twelve months, against 85% historically, because the projects have gotten bigger.

Quanta Services, which builds and maintains high-voltage transmission lines and substations for utilities and does much of it on live wire, said the same thing in a different form. Its record backlog reached $53.4bn, up 50%, but management noted that the big 765- and 500-kilovolt corridors are still in engineering, with field execution starting in the second half of 2027, and that roughly 95% of its generation work is not in backlog at all and runs past 2030.

That is a description of a very long-dated asset. On 17 and 18 August, the 30-year Treasury yield topped 5.31% and then 5.323%, its highest since 2007, on inflation, fiscal supply and uncertainty about policy under the new Federal Reserve chair. In the four sessions from that close, Quanta fell 8.9% and EMCOR 8.7%. Neither had spoken to the market since 30 July.

The businesses went the other way

Quanta's revenue growth accelerated for four straight quarters — 15.6%, then 19.6%, 26.3% and 41.1% — reaching $9.56bn in the June quarter. Gross margin widened 296 basis points year over year to 16.2%, and gross profit grew 72.8% on 41.1% more revenue, which is what operating leverage looks like when it is real. Two honest deductions: four acquisitions closed in the quarter will contribute $1.2–1.4bn of this year's revenue, so part of the growth is bought; and Quanta does not disclose data-center work as a dollar line anywhere in its statements. The "15–20% of revenue" figure for technology and load-center work is spoken commentary on a call.

EMCOR does disclose it. Electrical construction revenue of $1.66bn rose 24% at a 13.9% operating margin, up 210 basis points, on network-and-communications work up 45%. Mechanical construction revenue of $2.3bn rose 31% with data-center revenue more than doubling — but margin there fell 110 basis points to 12.5% as the mix shifted toward guaranteed-maximum-price and construction-manager contracts, which cap the upside. Company-wide operating margin still set a record at 10.6%.

Against that, both multiples compressed. Quanta's price per dollar of trailing gross profit is 20.33x, against roughly 26.8x on 21 May and 22.7x in February, even as trailing gross profit grew to $4.73bn. EMCOR's is 9.37x, against about 11.0x at both earlier dates. Gross profit is the usable lens here because Quanta's 72x trailing earnings are distorted by acquisition amortization; on enterprise value to EBITDA it is 33.7x against EMCOR's 14.9x, so the two are not priced as the same business.

What the group number hides

The five specialist builders most often grouped together fell about 15.5% on average over thirty days, but that average is three unrelated events. Sterling Infrastructure broke 31% in six sessions in late July on its own print. MasTec fell 18.5% on 31 July despite record backlog, after cutting its communications outlook on wireless slowdowns and wireline work deferred into 2027. Quanta, over the identical thirty days, was up 1.5%.

Dycom Industries is the control that decides which story this is. It builds fiber for carriers and cable operators rather than content inside data halls, and its 50-day average crossed below its 200-day on 19 August — five sessions before it reports, so the move cannot be its own news. Its fiscal first quarter grew 56.1%, but gross margin slipped to 14.0% from 15.0%, and MasTec's cut is a live read-across into Dycom's 26 August call.

One constraint sits under all of it, and it is not demand. The binding limit is craft labor — electricians, pipe fitters, supervisors. EMCOR spent roughly $750m in the quarter buying five union electrical contractors with $625m of revenue between them. It was buying crews.

The setup

Where it stands — Both protagonists raised guidance in July and de-rated in August on no company news, alongside a 19-year high in long yields.

Would confirm — Quanta and EMCOR report September-quarter backlog and remaining performance obligations still growing double digits year over year.

Would invalidate — EMCOR's twelve-month burn rate falls below 75%, or either company's book-to-bill drops under 1.

Watch next — Dycom reports fiscal second-quarter results on 26 August, guided to $1.94–2.01bn of contract revenue.

Valuation — Quanta at 20.33x trailing gross profit and 16.92x forward, versus about 26.8x in May; EMCOR 9.37x and 8.57x, versus 11.0x.