Ciena (NYSE: CIEN): BlackRock reports 10.3% beneficial stake in amended 13G

Rhea-AI Filing Summary

BlackRock, Inc. has filed an amended Schedule 13G reporting its beneficial ownership of 14,537,914 shares of Ciena Corporation common stock, representing 10.3% of the class as of the event date 11/30/2025. BlackRock reports sole power to vote 13,714,981 of these shares and sole power to dispose of 14,537,914 shares, with no shared voting or dispositive power.

The filing explains that these holdings reflect securities beneficially owned, or deemed to be beneficially owned, by certain BlackRock business units, and excludes other disaggregated units. It also notes that various persons have rights to dividends or sale proceeds from Ciena stock, but no individual holds more than five percent of the total outstanding common shares. BlackRock certifies that the securities were acquired and are held in the ordinary course of business and not for the purpose of changing or influencing control of Ciena.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 4)

CIENA CORPORATION

(Name of Issuer)

Common Stock

(Title of Class of Securities)

171779309

(CUSIP Number)

11/30/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. 171779309

1

Names of Reporting Persons

BlackRock, Inc.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 13,714,981.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 14,537,914.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

14,537,914.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

10.3 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: CIENA CORPORATION
(b)	Address of issuer's principal executive offices: 7035 RIDGE ROAD HANOVER MD 21076
Item 2.
(a)	Name of person filing: BlackRock, Inc. In accordance with SEC Release No. 34-39538 (January 12, 1998), this Schedule 13G reflects the securities beneficially owned, or deemed to be beneficially owned, by certain business units (collectively, the "Reporting Business Units") of BlackRock, Inc. and its subsidiaries and affiliates. It does not include securities, if any, beneficially owned by other business units whose beneficial ownership of securities are disaggregated from that of the Reporting Business Units in accordance with such release.
(b)	Address or principal business office or, if none, residence: BlackRock, Inc., 50 Hudson Yards New York, NY 10001
(c)	Citizenship: See Item 4 of Cover Page
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 171779309
Item 4.	Ownership
(a)	Amount beneficially owned: 14537914
(b)	Percent of class: 10.3 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 13714981
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 14537914
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. Various persons have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of the common stock of CIENA CORPORATION. No one person's interest in the common stock of CIENA CORPORATION is more than five percent of the total outstanding common shares.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. See Exhibit 99
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

BlackRock, Inc.

Signature:	Spencer Fleming
Name/Title:	Managing Director
Date:	12/04/2025

Exhibit Information

Exhibit 24: Power of Attorney Exhibit 99: Item 7

FAQ

What ownership stake in CIEN does BlackRock report in this Schedule 13G/A?

BlackRock reports beneficial ownership of 14,537,914 shares of Ciena Corporation (CIEN) common stock, representing 10.3% of the outstanding class.

How much voting power does BlackRock have over CIEN shares?

BlackRock reports sole voting power over 13,714,981 Ciena shares and no shared voting power, indicating it alone can vote those shares.

What dispositive power does BlackRock report over CIEN stock?

BlackRock has sole dispositive power over 14,537,914 Ciena shares and no shared dispositive power, meaning it alone can decide whether to sell or otherwise dispose of those shares.

Is BlackRock seeking to influence control of Ciena Corporation (CIEN)?

No. BlackRock certifies that the Ciena securities were acquired and are held in the ordinary course of business and not for the purpose of changing or influencing control of the company.

Who ultimately benefits from the CIEN shares held by BlackRock?

The filing states that various persons have rights to dividends or sale proceeds from Ciena stock held by BlackRock, but no single person has an interest in more than 5% of Ciena's total outstanding common shares.

Which BlackRock entities are included in this CIEN ownership report?

The ownership reflects securities beneficially owned, or deemed beneficially owned, by certain Reporting Business Units of BlackRock, Inc. and its subsidiaries and affiliates, excluding other business units that are disaggregated under SEC guidance.