Comfort Systems grew revenue 53.7%, backlog nearly doubled to $17.8 billion, and the stock fell
The contractor that cools and wires AI data centers grew revenue 54% and nearly doubled its backlog in a year, and the stock still fell. The filing shows what the market is arguing about: growth is arriving as estimate revisions and customer prepayments while gross margin sits still.
Richard Tang · 2 min read
Comfort Systems USA−8.12% — Comfort Systems USA, down 8.12 percent today, the Houston contractor that cools and wires AI data centers, filed the biggest quarter in its history on October 22 1. Revenue grew 53.7% from a year earlier, to a record $3.77 billion 1. Its backlog of contracted work nearly doubled in twelve months, to $17.8 billion 1. Earnings and revenue beat Wall Street's estimates for the sixth quarter running 2.
The stock still fell the morning after, to $1,146, in a slide tied to anxiety over who funds AI capital spending 3, and it now trades about 45% below its June high 3. The quarter is evidence that the buildout's binding constraint has moved downstream, from chips to the crews that install cooling and power. The market's complaint is that the margin line has not yet charged for it.
Quarterly revenue has nearly tripled since 2023 as data-center work took over
Data
| Revenue | |
|---|---|
| Q3 '23 | $1.38B |
| Q4 '23 | $1.36B |
| Q1 '24 | $1.54B |
| Q2 '24 | $1.81B |
| Q3 '24 | $1.81B |
| Q4 '24 | $1.87B |
| Q1 '25 | $1.83B |
| Q2 '25 | $2.17B |
| Q3 '25 | $2.45B |
| Q4 '25 | $2.65B |
| Q1 '26 | $2.87B |
| Q2 '26 | $3.27B |
| Q3 '26 | $3.77B |
The chain now runs from a GPU to a pipefitter
AI models need compute, compute needs buildings, and buildings need cooling, switchgear and wiring, which is mechanical and electrical contracting. Technology customers, mostly data centers, produced 61% of this quarter's revenue 1. A year ago the share was 46% 1. The backlog doubling was organic: same-store backlog reached $17.4 billion 4, and chief executive Brian Lane called the demand "relentless" 4.
Growth is arriving as revisions and prepayments, not price
Gross margin held flat at 24.8% 5. Comfort Systems recognizes revenue as costs are incurred, so upward revisions on jobs already underway added 4.5% to the quarter 1. The cash line is sharper. Nine-month operating cash flow reached $2.54 billion 1. Most of it, $1.69 billion, was customers paying before the work is done 1.
Gross margin climbed for two years, then flattened near 25% as revenue took off
Data
| Gross margin | |
|---|---|
| Q2 '23 | 17.6% |
| Q3 '23 | 20.1% |
| Q4 '23 | 20.6% |
| Q1 '24 | 19.3% |
| Q2 '24 | 20.1% |
| Q3 '24 | 21.1% |
| Q4 '24 | 23.2% |
| Q1 '25 | 22% |
| Q2 '25 | 23.5% |
| Q3 '25 | 24.8% |
| Q4 '25 | 25.5% |
| Q1 '26 | 26.3% |
| Q2 '26 | 25.9% |
Advance payment is what scarcity looks like from the buyer's side. The 10-Q expects demand to stay high through 2027 while labor costs and supply delays persist 1, and the company spent $211 million in the quarter on capacity, including a Texas modular builder that shifts work from job site to factory 21.
Succession lands on top of the open question
No forward guidance came with the release 6. Bill George, chief financial officer since 2005 and a founder of the company, retires once the annual report is filed, and chief accounting officer Julie Shaeff takes over 7. Friday morning's conference call is the first test of both. The bear case is that backlog can be canceled, and the company itself warns it has limited predictive value 8.
Customers do not prepay on this scale for work they expect to cancel. The projection, and it is one: flat margin turns into pricing power as the labor constraint binds. The prepayment line is the evidence, and the call is where it gets tested.
What happens next
FIXDoes incoming CFO Julie Shaeff signal any change in how growth is priced?
The case for
Backlog nearly doubled organically to $17.8 billion, with same-store backlog at $17.4 billion
The case against
Gross margin held at 24.8% despite 54% revenue growth, so scale is not yet buying price
- February 2027Annual report filing and CFO handover.
- April 2027First-quarter 2027 results. Does gross margin finally rise as the labor constraint binds?
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