Comfort Systems USA (FIX) Q3 2026 earnings review
Comfort Systems USA backlog jumps, but gross margin dips
Comfort Systems USA, a nationwide heating, cooling and electrical contractor, added a record pile of future orders even as project gross margin slipped from last quarter's peak. Third-quarter revenue rose 54% from a year ago to $3.77 billion, beating what the prior second-half outlook pointed to, by our math, while backlog from businesses owned a year ago climbed 85% to $17.39 billion. Customers also sent more upfront cash deposits, which pushed operating cash flow past $1 billion.
| Same-store backlog | $17.39B +85.4% from a year ago |
|---|---|
| Revenue | $3.77B +53.7% from a year ago |
| Gross profit margin | 24.8% down from 25.9% last quarter |
| 2026–2027 outlook | Held qualitative growth and profit view extended into 2027 |
⚖️ Verdict: 🟢 Bullish
The story got better because the $3.8 billion quarterly jump in contracted backlog — the largest in the company's history — extends visibility into 2027 and 2028 and eased fears of a second-half order pause. One caution: gross margin slipped 1.1 percentage points from the second quarter to 24.8%, falling below the recent range management expected to hold, while nine-month factory spending reached $499 million.
The question now is whether the record backlog and customer prepayments show broadening demand or just two giant tech buyers locking up factory space at the top of the cycle. The upcoming quarterly filing and conference call will show how much of the quarter's profit relied on prior-period accounting adjustments and whether tech concentration rose further.
🐂 Bull Case
Backlog Added a Record $3.8 Billion
Backlog is the total value of signed construction contracts that Comfort Systems USA has not yet completed. Even as the contractor burned through a record $3.77 billion of revenue this quarter, customers signed enough new work to push total backlog up by $3.75 billion from June, reaching $17.81 billion. Critics note that giant modular orders make quarterly additions lumpy, and that this surge may reflect a handful of tech customers locking in factory space early.
- Total backlog: $17.81 billion, up 90.0% from $9.38 billion a year ago
- Underlying backlog (from businesses owned a year ago): $17.39 billion, up 85.4% from a year ago
- Quarterly underlying backlog addition: $3.69 billion, by our math, compared with $1.26 billion in the same quarter last year
Chief executive Brian Lane said "Relentless demand, together with our competence and reputation, produced sequential backlog growth of $3.8 billion, and a year over year backlog increase exceeding $8.0 billion." This matters because underlying backlog grew 85.4%, outpacing revenue growth of 53.7% and widening the company's cushion of future work.
What to watch: the backlog schedule in the upcoming quarterly filing. It will show what share of the $17.81 billion converts to revenue over the next 12 months versus stretching into 2028.
Customer Prepayments Drove $1 Billion in Cash
Billings in excess of costs — cash payments from customers for work the company has not yet performed — sit on the balance sheet as a liability until crews build the projects. While bears warn that a booking slowdown would force this $3.87 billion balance to unwind and drain cash, customers kept paying upfront this quarter to secure capacity.
By our math, these advance billings jumped by $640.9 million from June to reach $3.87 billion, more than double the $1.73 billion balance a year ago. Because customers funded the work ahead of time, Comfort Systems USA generated $1.01 billion in operating cash flow and $805.6 million in free cash flow, which leaves $2.11 billion of net cash on the balance sheet.
What to watch: billings in excess of costs in the fourth quarter. A drop in that balance would show that the contractor is burning through customer prepayments faster than new deposits arrive.
Sales Beat the Implied Second-Half Plan
Three months ago, management forecast that full-year sales from businesses owned a year ago would rise in the mid-to-high 30% range, warning of tough comparisons in the second half. By our math, that full-year plan pointed to total second-half revenue of $6.7 billion to $6.9 billion, or roughly $3.4 billion per quarter.
Comfort Systems USA delivered $3.77 billion in the third quarter, up 53.7% from a year ago and 10.8% above the quarterly pace implied by the outlook. Selling and administrative overhead fell from 9.4% of revenue a year ago to 8.3%, lifting operating margin by 1.1 percentage points to 16.6%. Beating the implied pace shows that the prior plan was cautious, though fourth-quarter comparisons remain steep.
What to watch: any updated full-year underlying revenue target on Friday's conference call. Without a raise, the old outlook would imply fourth-quarter revenue near $3.03 billion, a 19% drop from the third quarter.
🐻 Bear Case
Gross Margin Slipped Below the Recent Range
"Strong ongoing demand and consistent excellence by our teams resulted in extraordinary results across every metric this quarter," chief executive Brian Lane said. Last quarter, management expected gross margin — the share of sales left after direct labor and materials — to stay within its recent range of 25.2% to 26.3%.
Gross margin did not stay in that range. Cost of services held at 75.2% of revenue, matching the year-ago quarter, which pulled gross margin down 1.1 percentage points from the second quarter's 25.9% to 24.8%. In the first half, retroactive profit adjustments on older contracts boosted revenue by nearly 8%, and the press release does not say whether that tailwind shrank in the third quarter.
What to watch: the footnote on prior-period contract estimate changes in the third-quarter filing. A drop from the second quarter's 7.7% of revenue would prove that underlying project margins are thinner than headline numbers suggest.
Factory Spending Multiplied Sixfold for Big Tech
To serve data-center customers, Comfort Systems USA is buying and equipping modular assembly factories rather than leasing them. Supporters view this build-out as a durable advantage backed by multi-year customer commitments, while bears see rising fixed costs tied to just two giant technology buyers.
Purchases of property and equipment hit $210.6 million in the third quarter, or 5.6% of revenue, up from $35.3 million (1.4% of revenue) a year ago. Over nine months, capital spending reached $499.4 million, more than doubling net property and equipment on the balance sheet from $388.0 million at year-end to $862.7 million. That larger asset base raised quarterly depreciation expense by 36.2% from a year ago to $21.9 million.
What to watch: modular factory square footage on the conference call. Management targeted 4 million square feet in production by year-end and 5 million by late summer 2027, which locks in higher fixed costs if data-center orders pause.
Risks This Quarter Didn't Answer
Four standing concerns depend on footnote and call disclosures that do not appear in the third-quarter earnings release.
- Prior-period estimate gains: added 7.7% to second-quarter revenue; the third-quarter filing's contract footnote will show how much they helped this quarter's 24.8% gross margin.
- Technology concentration: reached 58.7% of sales in the second quarter; the filing's customer table will show whether data centers passed 60% of revenue.
- Modular standalone economics: management has never disclosed standalone modular margins or returns despite spending $499.4 million on capital assets this year.
- Labor and siting constraints: headcount growth, wage inflation on multi-year contracts, and local power or permitting delays require commentary on Friday's call.
💲 Other KPIs
Billed receivables — invoices sent to customers that have not yet been paid — rose 66.4% from $2,306.3 million a year ago, outpacing the 53.7% rise in third-quarter revenue. From December's $2,577.9 million balance, billed receivables have climbed $1,259.4 million, though advance customer deposits still exceeded that working-capital build.
Cash minus total debt reached $2,108.5 million by our math, up from $1,800.7 million in June and $836.7 million at year-end. Total debt fell from $145.2 million in December to $49.6 million. Alongside the rising cash balance, the board raised the quarterly dividend to $0.90 per share, up from $0.80 in the second quarter and $0.50 a year ago.
Diluted shares shrank 0.6% from 35.37 million a year ago and edged down 0.3% from 35.25 million in the second quarter. In the first half, the electrical and mechanical contractor slowed share buybacks to $8.2 million while spending $573.7 million on total financing outflows over the first nine months, including debt payoff and dividends.
🔮 Guidance
Unchanged. Chief executive Brian Lane said "through year end and for 2027 we are well-positioned to grow organically, and to maintain high levels of profitability and solid ongoing cash flow." The press release gives no numerical ranges; management typically provides same-store growth rates on the conference call. By our math, the prior second-half revenue plan of $6.7–6.9 billion would leave just $3.03 billion (+14.7% from a year ago) for Q4 unless raised.
❓ Key Questions
How much did prior-period contract adjustments add to third-quarter revenue?
Retroactive estimate changes on older jobs added 7.7% to second-quarter sales. With gross margin dipping 1.1 percentage points from June to 24.8%, investors need the third-quarter figure to tell whether underlying project margins weakened or one-off gains simply normalized.
What is the updated full-year underlying revenue growth plan?
Third-quarter sales of $3.77 billion beat the quarterly run rate implied by the second-quarter call's mid-to-high 30% full-year target. Management has raised its annual plan three quarters in a row and has not yet given a fourth-quarter number.
What share of the $3.8 billion backlog jump came from two customers?
Same-store backlog jumped $3.69 billion in three months, and advance customer billings rose $640.9 million. Sizing how much of that commitment came from the two largest hyperscale buyers shows how concentrated the 2027–2028 pipeline has become.
What are the standalone margins and returns on the modular factories?
Comfort Systems USA spent $499.4 million on property and equipment over nine months, more than doubling its fixed asset base to build out modular capacity. Management still reports only mechanical and electrical segments, leaving modular profitability hidden.