FMR LLC and Abigail Johnson disclose 13.5% CIENA CORP (CIEN) ownership in 13G/A

Rhea-AI Filing Summary

FMR LLC reported beneficial ownership of 19,113,537.72 shares of CIENA CORP common stock, representing 13.5% of the class as of 06/30/2026. FMR LLC has sole dispositive power over all reported shares and sole voting power over 19,040,612.61 shares, with no shared voting or dispositive power.

Abigail P. Johnson is also reported as a beneficial owner with sole dispositive power over the same 19,113,537.72 shares, representing 13.5% of the class. One or more other persons have rights to dividends or sale proceeds, including Fidelity Growth Company Commingled Pool, whose interest amounted to 7,942,028.00 shares or 5.6% of CIENA CORP’s outstanding common stock at 06/30/2026.

Key Figures

Beneficial ownership: 19,113,537.72 shares Percent of class: 13.5% Sole voting power: 19,040,612.61 shares +3 more

6 metrics

Beneficial ownership 19,113,537.72 shares Shares of CIENA CORP common stock beneficially owned by FMR LLC

Percent of class 13.5% Portion of CIENA CORP common stock class beneficially owned as of 06/30/2026

Sole voting power 19,040,612.61 shares CIENA CORP shares over which FMR LLC has sole voting power

Sole dispositive power 19,113,537.72 shares CIENA CORP shares over which FMR LLC has sole dispositive power

Fidelity Growth Company Commingled Pool holding 7,942,028.00 shares Interest in CIENA CORP common stock, 5.6% of total outstanding at 06/30/2026

Fidelity Growth Company Commingled Pool percent 5.6% Percent of CIENA CORP outstanding common stock held at 06/30/2026

Key Terms

beneficially owned, Sole Voting Power, Sole Dispositive Power, Schedule 13G, +1 more

5 terms

beneficially owned financial

"Amount beneficially owned: 19113537.72"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

Sole Voting Power financial

"5 | Sole Voting Power 19,040,612.61"

Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.

Sole Dispositive Power financial

"7 | Sole Dispositive Power 19,113,537.72"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

Schedule 13G regulatory

"Please see Exhibit 99 for 13d-1(k) (1) agreement."

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

commingled pool financial

"The interest of Fidelity Growth Company Commingled Pool, in the COMMON STOCK"

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/06/2026 - 10:18 AM Accepted by SEC EDGAR 08/06/2026 - 10:17 AM Learn about SEC filing dates

FAQ

What percentage of CIENA CORP (CIEN) shares does FMR LLC beneficially own?

FMR LLC beneficially owns 19,113,537.72 shares of CIENA CORP common stock, representing 13.5% of the outstanding class as of 06/30/2026. This ownership is reported with sole dispositive power and no shared voting or dispositive power.

What is Abigail P. Johnson’s reported interest in CIENA CORP (CIEN)?

Abigail P. Johnson is reported with sole dispositive power over 19,113,537.72 shares of CIENA CORP common stock, equal to 13.5% of the class. The filing lists no shared voting or dispositive power for her position.

How many CIENA CORP (CIEN) shares does FMR LLC have sole voting power over?

FMR LLC has sole voting power over 19,040,612.61 shares of CIENA CORP common stock. It reports 0.00 shares with shared voting power and 0.00 shares with shared dispositive power in this Schedule 13G/A filing.

Which other entity holds more than 5% of CIENA CORP (CIEN) through FMR LLC’s structures?

The filing notes that Fidelity Growth Company Commingled Pool held 7,942,028.00 shares of CIENA CORP, equal to 5.6% of the total outstanding common stock at 06/30/2026, with rights to dividends or sale proceeds.

Does FMR LLC report any shared voting or dispositive power in CIENA CORP (CIEN)?

No. FMR LLC reports 0.00 shares with shared voting power and 0.00 shares with shared dispositive power. All reported 19,113,537.72 shares are subject to sole dispositive power, with most also under sole voting power.

What type of CIENA CORP (CIEN) security is covered in this Schedule 13G/A?

The filing covers CIENA CORP COMMON STOCK with CUSIP 171779309. FMR LLC and Abigail P. Johnson report their beneficial ownership and related voting and dispositive powers over this class of securities as of 06/30/2026.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 5)

CIENA CORP

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

171779309

(CUSIP Number)

06/30/2026

(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)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 171779309

1

Names of Reporting Persons

FMR LLC

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 19,040,612.61
6	Shared Voting Power 0.00
7	Sole Dispositive Power 19,113,537.72
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

19,113,537.72

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)

13.5 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP Number(s): 171779309

1

Names of Reporting Persons

Abigail P. Johnson

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

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 19,113,537.72
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

19,113,537.72

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)

13.5 %

12

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: CIENA CORP
(b)	Address of issuer's principal executive offices: 7035 Ridge Road,Hanover,MD,US,21067
Item 2.
(a)	Name of person filing: FMR LLC
(b)	Address or principal business office or, if none, residence: 245 Summer Street, Boston, Massachusetts 02210
(c)	Citizenship: Not applicable
(d)	Title of class of securities: COMMON STOCK
(e)	CUSIP No.: 171779309
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 19113537.72
(b)	Percent of class: 13.5 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: Please see the responses to Items 5 and 6 on the cover page.
	(ii) Shared power to vote or to direct the vote: 0.00
	(iii) Sole power to dispose or to direct the disposition of: 19113537.72
	(iv) Shared power to dispose or to direct the disposition of: 0.00
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. One or more other persons are known to 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 CORP. The interest of Fidelity Growth Company Commingled Pool, in the COMMON STOCK of CIENA CORP, amounted to 7942028.00 shares or 5.6% of the total outstanding COMMON STOCK at 06/30/2026.
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 attached 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.

FMR LLC

Signature:	Stephanie J. Brown
Name/Title:	Duly authorized under Power of Attorney effective as of January 3, 2023, by and on behalf of FMR LLC and its direct and indirect subsidiaries*
Date:	08/05/2026

Abigail P. Johnson

Signature:	Stephanie J. Brown
Name/Title:	Duly authorized under Power of Attorney effective as of January 26, 2023, by and on behalf of Abigail P. Johnson**
Date:	08/05/2026

Comments accompanying signature: * This power of attorney is incorporated herein by reference to Exhibit 24 to the Schedule 13G filed by FMR LLC on January 10, 2023, accession number: 0000315066-23-000003. ** This power of attorney is incorporated herein by reference to Exhibit 24 to the Schedule 13G filed by FMR LLC on January 31, 2023, accession number: 0000315066-23-000038.

Exhibit Information

Please see Exhibit 99 for 13d-1(k) (1) agreement.