Is There A Risk Hiding In Ciena Stock’s Growth?

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About half of Ciena’s business now comes directly from hyperscalers, the largest cloud companies, management said on its fiscal Q3 2026 earnings call. This leaves a Ciena (CIEN) holder counting on one group of buyers for half the company’s business, with two customers each making up more than 10% of revenue in that quarter. If those buyers slow their spending, all of Ciena would feel it. So why has so much of Ciena’s business shifted toward these buyers?

Why Ciena’s Sales Have Shifted Toward Cloud Companies

Management says the demand comes from large and growing investments in data center infrastructure, calling this the very early stage of a multiyear network investment era. Ciena’s revenue climbed 37% from a year earlier to $1.67 billion in fiscal Q3 2026. Revenue from cloud providers buying directly from Ciena grew over 80% in the same quarter, meaning that business is growing much faster than the rest of the company.

Management also said the share of revenue from sales in and around the data center has quadrupled since the start of fiscal 2026, moving ahead of the threefold rise it had committed to. The part of Ciena tied to data center buyers is still getting bigger, not settling down.

What Ciena Has Booked And Committed For This Demand

Ciena ended fiscal Q3 2026 with $8.5 billion of backlog, or orders not yet shipped, against $6.02 billion of revenue over the last twelve months. Management expects backlog to end the fiscal year above $10 billion, and it recently secured a large increase in customer commitments that extend through 2029. Those orders are the best evidence that the demand is real.

Ciena has also put money behind that demand. Management said its June convertible debt issue provided the capital to help secure supply over the next three years, and it expects cash from operations to fall in fiscal Q4 2026 as it pays for long-term supply agreements.

The open question is what these buyers spend once those commitments are filled. Management noted that Ciena is substantially insulated over the next two years from the pacing of new greenfield data center construction, as demand remains primarily driven by interconnect upgrades within existing facilities. It also expects steady growth in sales to service providers over the next few years, which would spread the business beyond the cloud companies.

How Far Has Ciena Stock Fallen In Past Shocks?

Ciena stock lost 49% in the 2022 inflation shock, its deepest fall of the five recent market shocks, against 24% for the SPDR S&P 500 ETF. In the 2025 tariff shock it lost 39%, compared with 19% for the ETF, so in both of its worst falls Ciena dropped about twice as far as the market. In the other three shocks, Ciena fell 17% in the 2023 banking crisis, against 6.7% for the ETF. In the 2023 yield shock and the 2024 yen unwind it fell 6.1% and 3.3%, less than the ETF’s 9.5% and 7.8%.

The shares have already come down, losing 33.8% between April 30 and October 29, 2026, while the S&P 500 returned 7.7%. Even so, Ciena trades at 75.9 times trailing earnings, against 22.8 for the S&P 500, so the price likely assumes the growth from cloud buyers keeps coming.

A high multiple can outlast the growth it prices in, and then the price rests on hope rather than results. A recent example: Tesla is still priced at about 12 times sales even though its deliveries fell two years in a row. Read Trefis Big Story: How Tesla Blundered.

A holder has reason for measured concern rather than alarm: the orders and the commitments are booked, but half the business depends on one group of buyers. For the risk to be worth taking, the cloud companies have to keep spending on data centers at this pace, and Ciena has to keep adding business outside that group. Ciena is expected to report its next results in December 2026, and revenue from cloud providers buying directly, set against total revenue, is the number to watch.

Sitting On A Big Gain In Ciena?

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