Sunbelt Rentals: The Cash Flow Gap in the Equipment Rental Boom

The big story in construction equipment right now isn't which projects are breaking ground — it's who owns the iron sitting on them. For two decades, contractors have been replacing equipment purchases with rental contracts, and mega projects have turned that trend into a structural shift. A project like Amazon's distribution network or the $12.5 billion O'Hare redevelopment needs massive equipment surges that drop off sharply once construction winds down. Buying that equipment means a 20-year depreciation schedule and idle assets afterward. Renting means deploying the machines exactly when they're needed, then pulling them out.

The American Rental Association projects U.S. equipment rental revenue at $83.5 billion this year, with growth accelerating from 3.4% to over 5% by 2028. Three companies dominate that pipeline: United Rentals (URI), Sunbelt Rentals (SUNB), and Herc Holdings (HRI), which between them plan to spend roughly $9.5 billion this year expanding their fleets.

But the headline growth number hides the story that matters to investors. General tool rental — the everyday excavators, scaffolds, and lifts — is growing in the mid-single digits. Specialty equipment — power generation, HVAC testing, load banks, trench safety, temporary electrical systems — is growing at twice that pace or more. Specialty growth, and the quality of the cash flow it generates, is what separates these three operators.

The specialty engine

Specialty equipment commands higher utilization and stickier contracts than general rental. A load bank testing a data center's power system doesn't get returned after a day — it stays on site for the duration of commissioning, sometimes months. Trench safety and temporary power are tied to project timelines, not daily discretion. This makes specialty revenue more durable and more predictable.

The numbers show the split clearly. In Sunbelt Rentals' first fiscal quarter of 2027 (ended July 2026), specialty rental revenue grew 25.3% while general tool grew 7.4%. More revealing than the growth rates is utilization: specialty equipment sits idle 23% of the time. General tool sits idle 53%, per the same report. That 30-percentage-point gap in utilization tells you where the assets earn their keep.

United Rentals shows the same pattern. In the second quarter of 2026, specialty equipment rental revenue grew 24.8% year over year against 6.6% for general equipment. Both companies are raising guidance and expanding capex — Sunbelt raised its full-year gross rental capex guidance to $2.75–$3.15 billion, up from $2.45–$2.85 billion. United Rentals' year-to-date gross capex stands at $2.9 billion for the first half alone.

This isn't a company trimming spending and signaling caution. It's the opposite: these operators are buying more iron because the demand profile — mega projects, data centers, power infrastructure — is convincing them that utilization will hold.

Cash flow quality separates the three

Here's where the investment question lives. Three companies, the same industry tailwinds, three very different cash flow profiles.

United Rentals is the scale leader with a $62 billion market cap and $16.7 billion in trailing revenue. It generates $5.7 billion in operating cash flow against $5.1 billion in capital expenditures, leaving $632 million in free cash flow — a 4% free cash flow margin on sales. Return on invested capital sits at 14.4%. Net debt stands at $14.1 billion, or about 1.5 times equity. The stock trades at 23.5 times earnings and 10.3 times EV/EBITDA. United is a machine that works, and the market prices it accordingly.

Sunbelt Rentals is half the size — $30.7 billion market cap, $11.2 billion in trailing revenue — but it generates free cash flow at a higher rate. Operating cash flow of $3.8 billion against $2.2 billion in capex leaves $1.6 billion in free cash flow, a 13.6% free cash flow margin. Return on invested capital is 22.3%. Net debt is $8.5 billion, or 1.1 times equity. On valuation, the stock trades at 22.1 times earnings and 8.5 times EV/EBITDA.

That EV/EBITDA gap — 8.5x for Sunbelt versus 10.3x for United — is the crack in the market. Sunbelt isn't a marginally worse version of United. It's generating cash per dollar of invested capital at a rate 55% higher, carrying less debt relative to equity, and growing its specialty segment faster. The market appears to be discounting it for size — it's a smaller player with international exposure (the UK segment, which declined 1.4% last quarter) — but the specialty growth rate and capital efficiency don't look like a company that deserves an 18% valuation discount.

Herc Holdings sits in an entirely different category. The company grew revenue 28.5% last year, largely from its $5.3 billion acquisition of H&E Equipment Services in June 2025, the largest buyout in industry history. But free cash flow is negative $128 million. Operating margin is 10% versus 25% for United and 20% for Sunbelt. Debt-to-equity is 4.2x versus 1.5x and 1.1x for the other two. Return on invested capital is 5.8%. Herc is a turnaround story — integrating a massive acquisition, getting margins back up, proving it can cover its debt. That's execution risk, not value. A low multiple doesn't rescue a company that can't generate free cash flow to service its leverage.

What the balance sheet says about durability

For the investor who needs to know whether the distribution and the business can survive a downturn, the numbers point in one direction. Sunbelt's net leverage ratio — management's own metric — is 1.8 times, well within its targeted range of 1.0 to 2.0. The company just completed a $1.2 billion senior notes offering at favorable rates (4.95% for 2030 maturities, 5.65% for 2036), and it shifted from semi-annual to quarterly dividends in September, signaling confidence in the cash flow stream.

United's balance sheet is equally disciplined: 1.8 times net leverage and $3 billion in liquidity. But United's free cash flow cushion is thinner — 4% of revenue versus Sunbelt's 13.6%. That matters when capex stays at multi-billion-dollar levels and the cycle turns. United can handle a downturn. Sunbelt has more breathing room.

The risk the numbers don't show

This is where the judgment gets harder. The rental model's advantage — redeployability — is also its vulnerability if the pipeline dries up. Mega projects are discrete and finite. When O'Hare finishes, when the current round of data center builds slows, the equipment comes off lease. The question is whether new projects fill the gap fast enough.

There are early signals to watch. Housing starts have stalled in recent data. Construction spending on home improvement has declined. And the specialty segment, while growing at 25%, is also the most concentrated in a small number of large customers and projects. A slowdown in data center buildouts — which drove much of the load bank and power growth — would hit the specialty numbers first and hardest.

Sunbelt's UK segment, which declined 1.4% last quarter and operates at 54% utilization, adds geographic risk that United doesn't carry. European construction has been softer, and that drag could persist.

Still, the structural case for rental over ownership doesn't disappear when one batch of projects ends. The economics — avoiding idle assets, converting capex to opex, redeploying across geographies — are why contractors have been renting for two decades, not two quarters. The gap between specialty growth and general growth suggests the mix shift itself is still underway.

The valuation gap

All things considered, the cash flow profile for Sunbelt is attractive. The company generates $1.6 billion in free cash flow on $11.2 billion in revenue — a margin that United, despite its scale advantage, cannot match. Return on invested capital of 22.3% is the kind of number that, in a competitive industry, suggests either a temporary tailwind or a structural edge. In Sunbelt's case, the specialty segment's higher utilization and more predictable contract terms point toward the latter.

The stock at 8.5 times EV/EBITDA is trading at a discount to United's 10.3x — a gap that would be reasonable if Sunbelt were materially worse. It isn't, on cash flow quality. The market is paying for United's scale and single-market focus while pricing Sunbelt's specialty growth as something smaller and less certain. Sunbelt itself disagrees with that reading, which is why it raised guidance across the board last week, including a meaningful increase in planned capex spending.

That doesn't guarantee the growth will hold, or that the multiple will close. But the gap between what the cash flow shows and what the price implies is the kind of discrepancy that, if the balance sheet holds, works in the investor's favor.