Is CLS a Buy? What to Consider in 2026
Short answer
The bull case for Celestica (CLS) rests on Hyperscaler-driven CCS growth: The Connectivity & Cloud Solutions segment is the engine of the story, reaching roughly ~$3.24 billion in Q1 2026 and growing about ~76% year over year. Q1 2026 revenue is ~$4.05B (up ~53% YoY). If you believe that thesis holds, the real questions become position sizing and overlap, not timing. The main risk to that view: Customer concentration is the headline risk: as of Q1 2026 three customers each represented at least 10% of revenue (roughly 35%, 15%, and 15%), and the top ten customers made up about ~78% of revenue, so losing or being de-prioritized by a single hyperscaler would matter a lot. Whether CLS is a buy comes down to whether you believe the thesis. This is informational, not a recommendation, and Walnut is not an investment adviser.
Celestica is a Toronto-based electronics manufacturing services (EMS) and supply-chain company that designs, builds, and tests hardware for other companies. It reports in two segments. Connectivity & Cloud Solutions (CCS) is the larger and faster-growing one, serving data-center and communications customers with networking switches, servers, storage, and increasingly custom AI/ML compute hardware; in Q1 2026 CCS was about ~80% of total revenue and grew roughly ~76% year over year, with hyperscaler customers making up the majority of that segment. Advanced Technology Solutions (ATS) is the diversified segment covering aerospace and defense, industrial, HealthTech, and capital equipment. The company makes money on the volume and complexity of the hardware it manufactures and on higher-value design and joint-design-manufacturing (JDM) work, where margins are structurally better than commodity contract assembly. Historically Celestica was a lower-margin, lower-multiple contract manufacturer competing on scale and efficiency. The shift toward AI infrastructure changed the story: demand for 800G networking switches and next-generation AI/ML compute programs from a concentrated set of hyperscaler customers drove rapid revenue growth and modest margin expansion, and the stock re-rated sharply as investors began treating it as an AI-infrastructure play rather than a traditional EMS name. Management has repeatedly raised guidance through 2025 and into 2026 on that demand.
What's the case for buying CLS?
Hyperscaler-driven CCS growth
The Connectivity & Cloud Solutions segment is the engine of the story, reaching roughly ~$3.24 billion in Q1 2026 and growing about ~76% year over year. Management guided to roughly ~70% CCS revenue growth for full-year 2026, driven by data-center demand from a concentrated hyperscaler customer base. This is what shifted Celestica from a traditional contract manufacturer into an AI-infrastructure name in investors' eyes.
AI networking and compute content
Growth is concentrated in specific high-demand products: 800G networking switches ramping across hyperscaler customers, and next-generation AI/ML compute programs. In Q1 2026 the communications end market grew about ~69% and the enterprise end market about ~101%, the latter tied to a planned hyperscaler AI/ML compute ramp. As AI clusters scale, the dollar content of networking and custom compute hardware per build has been rising.
Margin expansion and mix
EMS has historically been a thin-margin business, but Celestica's adjusted operating margin reached about ~8.0% in Q1 2026, up roughly 90 basis points year over year, with full-year 2026 guidance around ~8.1%. The improvement reflects scale and a richer mix toward higher-value design and CCS work rather than commodity assembly. Whether margins hold or expand further is a key part of the valuation debate.
Design and JDM differentiation
Celestica increasingly competes on joint-design-manufacturing (JDM) and engineering, not just assembly, which helped it take a leading slice of the high-speed Ethernet switch market versus EMS rivals. Deeper design involvement tends to carry better margins and stickier customer relationships. This is the lever the company points to for sustaining differentiation if pure-volume competition intensifies.
What are the risks to CLS?
Customer concentration is the headline risk: as of Q1 2026 three customers each represented at least 10% of revenue (roughly 35%, 15%, and 15%), and the top ten customers made up about ~78% of revenue, so losing or being de-prioritized by a single hyperscaler would matter a lot. EMS has historically run thin margins, leaving limited cushion if pricing or volumes compress. The business is tied to AI capital spending, which is cyclical and could slow or pause after a heavy buildout phase. And the stock has re-rated to a much higher multiple than its EMS history, so it carries both competition from Jabil, Flex, Foxconn, and ODMs and the risk that high growth expectations are not met.
How is CLS valued? (as of June 2026)
- Q1 2026 revenue: ~$4.05B (up ~53% YoY)
- CCS segment growth: ~76% YoY in Q1 2026 (~80% of revenue)
- 2026 revenue guidance: ~$19B (raised from ~$17B)
- Adjusted operating margin: ~8.0% Q1 2026; ~8.1% 2026 guide
- P/E ratio: ~40-52x (varies by source/date)
- Market capitalization: ~$38-39B
These figures are tied to the June 2026 reporting picture and Celestica's Q1 2026 results announced in late April 2026. The company has repeatedly beaten and raised guidance on AI-driven demand, and its valuation multiple has expanded well above its historical EMS range to reflect those growth expectations. A premium multiple means the stock is more sensitive to any disappointment in growth or margins than a traditional contract manufacturer would be.
How do you decide if CLS is a buy?
Rather than asking whether CLS is a buy in the abstract, it tends to help to answer four questions:
- Thesis: do you believe the case above, and is it still true today?
- Time horizon: a single stock can be volatile, so a longer horizon absorbs more of the swings.
- Position sizing: a thesis can be right and the sizing still wrong; decide how much of your portfolio one name should be.
- Overlap: check whether you already hold CLS indirectly through an index or sector ETF before adding more.
For the full picture, see the CLS stock guide (what the company does, the ETFs that hold it, similar stocks, and the themes it fits). In Walnut you can ask its AI about CLS against your real portfolio and see your actual exposure before deciding.
The bottom line on CLS
The bottom line: Celestica's story right now is Hyperscaler-driven CCS growth, with q1 2026 revenue at ~$4.05B (up ~53% YoY). If you believe that narrative continues, the call is about sizing CLS sensibly and checking overlap with what you own; if you doubt it (the risk: customer concentration is the headline risk: as of Q1 2026 three customers each represented at least 10% of revenue (roughly 35%, 15%, and 15%), and the top ten customers made up about ~78% of revenue, so losing or being de-prioritized by a single hyperscaler would matter a lot.), it is not for you. Decide from the thesis, not the ticker. Walnut is not an investment adviser.
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FAQ
Is CLS a good stock to buy right now?
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The case for Celestica right now is Hyperscaler-driven CCS growth, with q1 2026 revenue at ~$4.05B (up ~53% YoY). If you believe that thesis holds, CLS is a way to own it and the real questions are sizing and overlap, not timing; the main risk to that view is customer concentration is the headline risk: as of Q1 2026 three customers each represented at least 10% of revenue (roughly 35%, 15%, and 15%), and the top ten customers made up about ~78% of revenue, so losing or being de-prioritized by a single hyperscaler would matter a lot. So it comes down to whether you believe the thesis. Walnut is not an investment adviser and this is not a recommendation.
What does Celestica do?
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Celestica is a Toronto-based electronics manufacturing services (EMS) and supply-chain company that designs, builds, and tests hardware for other companies.
What are the main risks of CLS?
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Customer concentration is the headline risk: as of Q1 2026 three customers each represented at least 10% of revenue (roughly 35%, 15%, and 15%), and the top ten customers made up about ~78% of revenue, so losing or being de-prioritized by a single hyperscaler would matter a lot. EMS has historically run thin margins, leaving limited cushion if pricing or volumes compress. The business is tied to AI capital spending, which is cyclical and could slow or pause after a heavy buildout phase. And the stock has re-rated to a much higher multiple than its EMS history, so it carries both competition from Jabil, Flex, Foxconn, and ODMs and the risk that high growth expectations are not met.
Is CLS a good stock to buy right now?
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That depends on your goals, time horizon, and risk tolerance, and this is not advice. The bull case is rapid CCS growth, AI networking and compute content, and rising margins from hyperscaler demand. The bear case is heavy customer concentration, historically thin EMS margins, exposure to a cyclical AI-capex cycle, and a much higher valuation than its past. Weigh both against your own situation.
What does Celestica do?
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Celestica is an electronics manufacturing services (EMS) company that designs, builds, and tests hardware for other companies. Its CCS segment makes networking switches, servers, storage, and custom AI/ML compute hardware for data-center and communications customers, while its ATS segment serves aerospace and defense, industrial, HealthTech, and capital-equipment markets. It earns money on manufacturing volume, complexity, and higher-value design work.
Does CLS pay a dividend?
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No. As of June 2026 Celestica does not pay a dividend to shareholders. Any return from holding the stock would come from changes in the share price rather than dividend income. That is common for companies reinvesting heavily into a fast-growing part of their business, though it means income-focused investors get no cash payout.
How does Celestica benefit from AI?
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Celestica builds the physical hardware behind AI data centers: 800G networking switches and custom AI/ML compute systems for hyperscalers. As cloud providers expand AI clusters, the dollar value of networking and compute hardware Celestica manufactures per build rises. In Q1 2026 its CCS segment grew about ~76% year over year, with hyperscalers making up most of that segment's revenue.
Walnut is informational and is not an investment adviser. This page is educational and not a recommendation to buy or sell CLS; figures are approximate and dated, and your own situation, time horizon, and risk tolerance should drive any decision. Verify current data before investing.