CAT vs SEI: Which Is the Better Buy in 2026?
Last updated August 2026
Short answer
CAT and SEI are similarly sized, but SEI trades noticeably cheaper on forward earnings (22.03x vs 26.76x): the market is paying up for CAT's profile and pricing SEI more conservatively, or for faster growth. Which you prefer comes down to the drivers you believe, and whether adding either over-concentrates what you already own.
CAT vs SEI: the tie-breaker metrics
Same yardstick, side by side (as of August 2026). Valuation lined up like this is most meaningful for two names in the same corner of the market, which these are. Figures are approximate; verify before investing.
| Metric | CAT | SEI | What it tells you |
|---|---|---|---|
| Forward P/E | 26.76 | 22.03 | Valuation on next year's expected earnings, the same yardstick for both. Lower is cheaper for that growth; higher means the market is paying up. |
| Trailing P/E | 40.66 | 61.20 | Valuation on the last 12 months. A big drop from trailing to forward means the market expects earnings to jump, so more growth is already in the price. |
| Beta | 1.57 | 1.18 | Volatility vs the market. Above 1 swings harder than the index; below 1 is steadier. Higher beta means bigger drawdowns to hold through. |
| Price vs 52-week range | 61% of range | 44% of range | Where today's price sits between the 52-week low and high. Near the high is momentum with less margin of safety; near the low is out of favor or a discount, depending on why. |
| Price / book | 20.11 | 3.84 | How much you pay over book value. Very high can signal an asset-light, high-return business or a rich price. |
Reading it: SEI is the cheaper of the two on forward earnings, but cheaper is not the same as better. Pair the valuation with growth (how far the forward P/E sits below the trailing P/E) and risk (beta) before you decide.
Before you buy: how CAT and SEI affect your concentration
The metrics above tell you which is the marginally better business. The bigger risk for most people is not picking the slightly worse stock, it is over-concentrating. CAT and SEI share themes, so owning both, or adding either to what you already hold, can quietly push a large share of your portfolio into one bet.
This is the part a generic comparison page cannot answer, because it depends on what you own. Connect your brokerage and Walnut shows your real, combined CAT and SEI exposure, flags overlap with your existing positions, and tells you if adding one would tip you past a concentration you are comfortable with, read-only by default, with your login staying at your broker. Walnut is not an investment adviser.
What does Caterpillar (CAT) do?
Caterpillar is the world's largest manufacturer of construction and mining equipment, and a major maker of diesel and natural gas engines, industrial gas turbines, and locomotives. It sells bulldozers, excavators, loaders, dump trucks, and related heavy machinery used in construction, mining, quarrying, and infrastructure, plus power systems and engines for oil and gas, marine, power generation, and data-center backup. Caterpillar makes money by selling new equipment through a global dealer network and, increasingly importantly, by selling high-margin aftermarket parts, services, and financing through Cat Financial. Its three core segments are Construction Industries, Resource Industries (mining), and Energy and Transportation. The company is highly cyclical, tied to global construction activity, commodity prices, and infrastructure spending, but its large installed base generates recurring service revenue that smooths the cycle. Caterpillar is headquartered in Irving, Texas, and sells worldwide.
What does Solaris Energy Infrastructure (SEI) do?
Solaris Energy Infrastructure (NYSE:SEI), formerly Solaris Oilfield Infrastructure (ticker SOI until September 2024), operates two segments. Solaris Power Solutions leases mobile natural-gas turbine power generation, control, and distribution equipment to data centers, energy operators, and industrial customers, while Solaris Logistics Solutions provides sand-handling and material-management systems used to complete oil and gas wells. The company has pivoted hard toward distributed power as demand from AI and data center buildouts has surged, expanding its power fleet and signing multiple long-term contracts with large technology firms, including one investment-grade customer for more than 600 MW under a 10-year term.
CAT vs SEI: how do they differ?
Both fit overlapping themes, but they are not interchangeable. The useful comparison is which set of drivers and risks you want exposure to.
- CAT drivers: Infrastructure and construction demand; Energy and data-center power.
- SEI drivers: AI and data center power demand; Fleet expansion and long-term contracts.
Which fits which kind of investor
A faster-growing, richer-valued name usually swings harder, so it suits a longer horizon and a higher tolerance for volatility; a steadier, more cash-generative business suits a more conservative or income-minded investor. The honest test is which set of risks you could hold through a drawdown: Caterpillar is deeply cyclical. For SEI, customer concentration is the dominant risk: as of late 2024 a single large customer accounted for the vast majority of power solutions revenue, so any contract change, delay, or non-renewal could sharply affect results.
CAT or SEI: which should you pick?
CAT vs SEI: the full fundamentals
CAT. Caterpillar trades as a high-quality cyclical: investors pay a moderate earnings multiple that reflects best-in-class margins, a wide dealer moat, and growing services revenue, balanced against the inherent volatility of construction and mining demand. The valuation tends to expand on infrastructure and data-center power optimism and contract when global growth signals soften.
SEI. SEI trades at a rich trailing P/E in the roughly 80 to 95 range, reflecting expectations that its contracted power fleet drives large forward earnings growth. Q1 2026 delivered record revenue near $196 million and Adjusted EBITDA of about $84 million, ahead of consensus, and management raised near-term EBITDA guidance. The company carries roughly $1.3 billion of net debt after refinancing, keeping leverage near 1.3 times EBITDA.
Headline figures (approximate, early 2026): CAT shows revenue (ttm) ~$65 billion, operating margin ~20%, net income (ttm) ~$10 billion, dividend yield ~1.5%, with a long growth record (Dividend Aristocrat); SEI shows revenue (ttm) ~$690M, revenue (fy2025) ~$622M, q1 2026 revenue ~$196M (up ~55% YoY), adjusted ebitda (ttm) ~$283M.
The bottom line: CAT vs SEI
CAT and SEI are related but distinct: same themes, different businesses and risks. Neither wins in the abstract; the right pick is whichever thesis you actually believe, sized so you are not over-concentrated in one theme. Walnut can show your combined CAT and SEI exposure against your real portfolio. It is not an investment adviser.
Wondering how CAT or SEI fits the portfolio you already own? Walnut is an AI investing app that connects your brokerage read-only and answers questions like that about your actual holdings: overlap, concentration, and how each position tracks the S&P 500. Compare the best AI portfolio analyzers or see the best AI investing apps in 2026.
Investing in Caterpillar with AI
Connect the broker you already use and ask Walnut's AI how CAT fits what you actually hold: whether you own it already through a fund, what it would do to your concentration, and how it has tracked the S&P 500. Read-only by default, and you approve anything before it reaches your broker.
FAQ
What is the difference between CAT and SEI?
+
Caterpillar is the world's largest manufacturer of construction and mining equipment, and a major maker of diesel and natural gas engines, industrial gas turbines, and locomotives. Solaris Energy Infrastructure (NYSE:SEI), formerly Solaris Oilfield Infrastructure (ticker SOI until September 2024), operates two segments. They show up together because they share investment themes, but they are different businesses, so the better fit depends on which thesis you are expressing.
Is CAT or SEI the better stock?
+
Neither is universally better; they suit different views and risk levels. Walnut is informational, not investment advice. Compare what each does, the tie-breaker metrics above, and the risks, then decide which fits your thesis and what you already own.
Which is cheaper, CAT or SEI?
+
On forward P/E (as of August 2026), CAT trades at 26.76x and SEI at 22.03x, so SEI is the cheaper of the two on next year's expected earnings. A lower multiple is not automatically the better buy: a richer valuation can be justified by faster growth, and a lower one can reflect real risk. Weigh the multiple against how fast each business is compounding.
Should you own both CAT and SEI?
+
Because they share themes, owning both concentrates you in that theme. That can be intentional (a focused bet) or accidental (less diversification than it looks). Walnut can show your combined exposure across both, and whether adding either over-concentrates you, before you buy.
What are the risks of CAT vs SEI?
+
CAT: Caterpillar is deeply cyclical. A global construction slowdown, falling commodity prices that curb mining capital spending, or a recession would cut equipment demand and pressure margins and the stock. The business is exposed to China and emerging-market construction, currency swings, and trade and tariff policy. Mining capital expenditure is lumpy and tied to volatile metals and energy prices. Long-term, electrification and shifts away from diesel could challenge parts of the engine business. Premium valuations reached during cyclical peaks can compress quickly when orders soften, and dealer inventory swings can amplify the volatility of reported results. SEI: Customer concentration is the dominant risk: as of late 2024 a single large customer accounted for the vast majority of power solutions revenue, so any contract change, delay, or non-renewal could sharply affect results. The valuation is demanding, with the stock trading at a large multiple of trailing earnings, leaving little room for execution stumbles or slowing AI-power demand. Rapid fleet expansion funded by roughly $1.3 billion of debt raises leverage and interest expense, and turbine delivery timelines are subject to supply chain and commissioning delays. The legacy logistics business remains tied to volatile oil and gas activity, and cash generation has historically been sensitive to commodity price swings. Broader risks include competition from larger equipment and power providers and the possibility that hyperscalers build or procure power capacity in-house.
Related comparisons
Browse all stock comparisons.
Walnut is informational, not investment advice. This page is descriptive and not a recommendation to buy or sell CAT or SEI; figures are approximate and dated (as of August 2026). Verify current data before investing.