Cover and table of contents

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

OR

Commission file number 001-36250

Ciena Corporation

(Exact name of registrant as specified in its charter)

Delaware

(State or other jurisdiction of

incorporation or organization)

7035 Ridge Road, Hanover, MD

(Address of principal executive offices)

23-2725311

(I.R.S. Employer

Identification No.)

21076

(Zip Code)

Registrant’s telephone number, including area code: (410**)** 694-5700

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes þ No o

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes o No þ

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes þ No o

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes þ No o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☑

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. o

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). o

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act) Yes ☐ No þ

The aggregate market value of the registrant’s Common Stock held by non-affiliates of the registrant as of May 3, 2025, the last business day of the registrant’s most recently completed second fiscal quarter, was approximately $10.3 billion based on the closing price of the Common Stock on the New York Stock Exchange on that date.

The number of shares of the registrant’s Common Stock outstanding as of December 5, 2025 was 140,854,735.

DOCUMENTS INCORPORATED BY REFERENCE

Part III of this annual report on Form 10-K (the “annual report”) incorporates by reference certain portions of the registrant’s definitive proxy statement for its 2026 Annual Meeting of Stockholders, which is expected to be filed with the Commission not later than 120 days after the end of the fiscal year covered by this annual report.

CIENA CORPORATION

ANNUAL REPORT ON FORM 10-K

FOR FISCAL YEAR ENDED NOVEMBER 1, 2025

TABLE OF CONTENTS

PART I

Cautionary Note Regarding Forward-Looking Statements

This annual report contains statements that discuss future events or expectations, projections of results of operations or financial condition, changes in the markets for our products and services, trends in our business, business prospects and strategies, and other “forward-looking” information. In some cases, you can identify “forward-looking statements” by words like “may,” “will,” “would,” “can,” “should,” “could,” “expects,” “future,” “plans,” “anticipates,” “believes,” “estimates,” “predicts,” “intends,” “potential,” “projects,” “targets,” or “continue” or the negative of those words and other comparable words. These statements may relate to, among other things: our competitive landscape; market conditions and growth opportunities; factors impacting our industry and markets, including macroeconomic conditions and global supply chain constraints; factors impacting the businesses of network operators, their network architectures and their adoption of next-generation network infrastructures; our strategy, including our research and development, supply chain and go-to-market initiatives and our efforts to increase the reach of our business into new or growing product, customer and geographic markets; our order volumes, backlog and seasonality in our business; expectations for our financial results, revenue, gross margin, operating expense and key operating measures in future periods; the adequacy of our sources of liquidity to satisfy our working capital needs, capital expenditures and other liquidity requirements; cybersecurity events; business initiatives including information technology (“IT”) and responsible business initiatives; the impact of changes in tax law and our effective tax rates; and market risks associated with financial instruments and foreign currency exchange rates. These statements are subject to known and unknown risks, uncertainties and other factors, and actual events or results may differ materially from any future results, activity, performance, or achievements expressed or implied by these forward-looking statements, including due to factors such as those set forth below in “Risk Factors Summary.”

For a discussion of additional important factors that could cause actual results to vary materially from those anticipated in the forward-looking statements, see “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and “Risk Factors” in this annual report. We operate in a very competitive and dynamic environment and new risks and uncertainties emerge, are identified or become apparent from time to time, and therefore may not be identified in this annual report. We cannot predict all risks and uncertainties that could have an impact on the forward-looking statements contained in this annual report. You should be aware that the forward-looking statements contained in this annual report are based on our current views and assumptions. We undertake no obligation to revise or update any forward-looking statements made in this annual report to reflect events or circumstances after the date hereof or to reflect new information or the occurrence of unanticipated events, except as required by law. The forward-looking statements in this annual report are intended to be subject to protection afforded by the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995. Unless the context requires otherwise, references in this annual report to “Ciena,” the “Company,” “we,” “us,” and “our” refer to Ciena Corporation.