Wellington Group discloses 6.0M Magnite (MGNI) shares held for clients

Rhea-AI Filing Summary

Wellington Management Group LLP, together with Wellington Group Holdings LLP and Wellington Investment Advisors Holdings LLP, reports beneficial ownership of 6,044,492 shares of Magnite, Inc. common stock, representing 4.22% of the class. These shares are held of record by clients of various Wellington investment advisers. The group reports 0 shares with sole voting or dispositive power, 3,568,479 shares with shared voting power, and 6,044,492 shares with shared dispositive power. The filing notes that no single client is known to hold more than five percent of this class.

Key Figures

Beneficial ownership: 6,044,492 shares Percent of class: 4.22% Shared voting power: 3,568,479 shares +3 more

6 metrics

Beneficial ownership 6,044,492 shares Magnite common stock beneficially owned by Wellington-related entities

Percent of class 4.22% Portion of Magnite common stock class reported as beneficially owned

Shared voting power 3,568,479 shares Shares over which Wellington entities report shared voting authority

Shared dispositive power 6,044,492 shares Shares over which Wellington entities report shared dispositive authority

Sole voting power 0 shares Shares over which Wellington entities report sole voting authority

Sole dispositive power 0 shares Shares over which Wellington entities report sole dispositive authority

Key Terms

beneficially owned, shared voting power, shared dispositive power, parent holding company, +1 more

5 terms

beneficially owned financial

"Amount beneficially owned: See the responses to Item 9 on the attached cover pages."

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.

shared voting power financial

"Shared Voting Power 3,568,479.00"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

shared dispositive power financial

"Shared Dispositive Power 6,044,492.00"

parent holding company financial

"The securities as to which this Schedule is filed by Wellington Management Group LLP, as parent holding company"

investment advisers financial

"The securities as to which this Schedule is filed are owned of record by clients of one or more investment advisers"

FAQ

What percentage of Magnite (MGNI) does Wellington currently report owning?

Wellington entities report beneficial ownership of 4.22% of Magnite’s common stock. This stake is held through shares owned of record by clients of various Wellington investment advisers rather than directly by the Wellington entities themselves.

How many Magnite (MGNI) shares are beneficially owned by Wellington?

Wellington reports beneficial ownership of 6,044,492 Magnite common shares. These securities are owned of record by clients of Wellington investment advisers, over which Wellington entities have shared voting and/or dispositive power as described in the filing.

Does Wellington have sole or shared voting power over its Magnite (MGNI) shares?

Wellington reports 0 shares with sole voting power and 3,568,479 shares with shared voting power. Voting authority relates to shares held for clients of Wellington investment advisers, rather than directly by Wellington entities.

What dispositive power does Wellington report over Magnite (MGNI) shares?

Wellington reports 0 shares with sole dispositive power and 6,044,492 shares with shared dispositive power. Dispositive power reflects the ability to direct the sale or other disposition of client-held shares.

Do any Wellington clients hold more than 5% of Magnite (MGNI) stock?

The filing states that no client of the Wellington investment advisers is known to have the right or power over more than five percent of Magnite’s common stock class referenced in this ownership report.

Which Wellington entities are included in this Magnite (MGNI) ownership report?

The report covers Wellington Management Group LLP, Wellington Group Holdings LLP, and Wellington Investment Advisors Holdings LLP, which collectively control various Wellington investment advisers whose clients own the Magnite shares of record.

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

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Available on EDGAR 08/13/2026 - 04:15 PM Accepted by SEC EDGAR 08/13/2026 - 04:13 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

Magnite, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

55955D100

(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): 55955D100

1

Names of Reporting Persons

Wellington Management Group LLP

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

MASSACHUSETTS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,568,479.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 6,044,492.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,044,492.00

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)

4.2 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP Number(s): 55955D100

1

Names of Reporting Persons

Wellington Group Holdings LLP

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 0.00
6	Shared Voting Power 3,568,479.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 6,044,492.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,044,492.00

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)

4.2 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP Number(s): 55955D100

1

Names of Reporting Persons

Wellington Investment Advisors Holdings LLP

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 0.00
6	Shared Voting Power 3,568,479.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 6,044,492.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,044,492.00

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)

4.2 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Magnite, Inc.
(b)	Address of issuer's principal executive offices: 1250 Broadway, 15th Floor, New York NY 10001
Item 2.
(a)	Name of person filing: Wellington Management Group LLP Wellington Group Holdings LLP Wellington Investment Advisors Holdings LLP
(b)	Address or principal business office or, if none, residence: c/o Wellington Management Company LLP, 280 Congress Street, Boston MA 02210
(c)	Citizenship: Wellington Management Group LLP - Massachusetts Wellington Group Holdings LLP - Delaware Wellington Investment Advisors Holdings LLP - Delaware
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 55955D100
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: See the responses to Item 9 on the attached cover pages.
(b)	Percent of class: 4.22 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: See the responses to Item 6 on the attached cover pages.
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: See the responses to Item 8 on the attached cover pages.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
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. The securities as to which this Schedule is filed are owned of record by clients of one or more investment advisers identified in Item 7 directly or indirectly owned by Wellington Management Group LLP. Those clients have the right to receive, or the power to direct the receipt of, dividends from, or the proceeds from the sale of, such securities. No such client is known to have such right or power with respect to more than five percent of this class of securities, except as follows: Not Applicable.
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. Pursuant to the instructions in Item 7 of Schedule 13G, the following lists the identity and Item 3 classification of each relevant entity that beneficially owns shares of the security class being reported on this Schedule 13G. Wellington Group Holdings LLP - HC Wellington Investment Advisors LLP - HC Wellington Management Global Holdings, Ltd. - HC One or more of the following investment advisers (the "Wellington Investment Advisers"): Wellington Management Company LLP - IA Wellington Management Canada LLC - IA Wellington Management Singapore Pte Ltd - IA Wellington Management Hong Kong Ltd - IA Wellington Management International Ltd - IA Wellington Management Japan Pte Ltd - IA Wellington Management Australia Pty Ltd - IA The securities as to which this Schedule is filed by Wellington Management Group LLP, as parent holding company of certain holding companies and the Wellington Investment Advisers, are owned of record by clients of the Wellington Investment Advisers. Wellington Investment Advisors Holdings LLP controls directly, or indirectly through Wellington Management Global Holdings, Ltd., the Wellington Investment Advisers. Wellington Investment Advisors Holdings LLP is owned by Wellington Group Holdings LLP. Wellington Group Holdings LLP is owned by Wellington Management Group LLP.
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.

Wellington Management Group LLP

Signature:	Matthew Revell
Name/Title:	Compliance Manager
Date:	08/14/2026

Wellington Group Holdings LLP

Signature:	Matthew Revell
Name/Title:	Compliance Manager
Date:	08/14/2026

Wellington Investment Advisors Holdings LLP

Signature:	Matthew Revell
Name/Title:	Compliance Manager
Date:	08/14/2026