Loomis Sayles (NASDAQ: SEIC) reports 7.19% SEI Investments stake

Rhea-AI Filing Summary

Loomis, Sayles & Co., L.P. reported beneficial ownership of 8,808,845.24 shares of SEI Investments Co common stock, representing 7.19% of the outstanding class as of 12/31/2025.

The firm has sole voting power over 7,264,083 of these shares and no shared voting or dispositive power. The securities are held for the benefit of its clients, none of whom individually holds more than 5% of the class. Loomis Sayles states the position is held in the ordinary course of business and not for changing or influencing control of SEI Investments.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 17)

SEI Investments Co

(Name of Issuer)

Common Stock

(Title of Class of Securities)

784117103

(CUSIP Number)

12/31/2025

(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. 784117103

1

Names of Reporting Persons

Loomis, Sayles & Co., L.P.

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 7,264,083.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

8,808,845.24

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)

7.19 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: SEI Investments Co
(b)	Address of issuer's principal executive offices: 1 FREEDOM VALLEY DRIVE, OAKS, PA, 19456-1100
Item 2.
(a)	Name of person filing: Loomis, Sayles & Co., L.P.
(b)	Address or principal business office or, if none, residence: One Financial Center Boston, MA 02111
(c)	Citizenship: United States
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 784117103
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: 8808845.24
(b)	Percent of class: 7.19 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 7264083.0
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 0
	(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. Clients of Reporting Person have such a right, none of whom has such interest relating to more than 5% of any class.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
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 andare held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect ofchanging or influencing the control of the issuer of the securities and were not acquired and are not held in connection withor as a participant in any transaction having that purpose or effect, other than activities solely in connection with anomination 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.

Loomis, Sayles & Co., L.P.

Signature:	Mari Shimokawa
Name/Title:	Deputy Chief Compliance Officer
Date:	02/12/2026

FAQ

How many SEI Investments Co (SEIC) shares does Loomis Sayles beneficially own?

Loomis, Sayles & Co., L.P. beneficially owns 8,808,845.24 SEI Investments Co common shares. This stake represents 7.19% of the company’s outstanding common stock as of December 31, 2025, according to the Schedule 13G/A ownership disclosure.

What percentage of SEI Investments Co (SEIC) does Loomis Sayles hold?

Loomis, Sayles & Co., L.P. reports beneficial ownership of 7.19% of SEI Investments Co’s common stock. This percentage is based on 8,808,845.24 shares held for its clients as of December 31, 2025, crossing the 5% reporting threshold.

What voting power does Loomis Sayles report over SEI Investments Co (SEIC) shares?

Loomis, Sayles & Co., L.P. has sole voting power over 7,264,083 SEI Investments Co shares and reports no shared voting power. It also reports no sole or shared dispositive power, meaning it does not control the decision to sell these shares under this filing.

Who ultimately benefits from Loomis Sayles’ SEI Investments Co (SEIC) holdings?

Loomis Sayles states that its clients have the right to receive dividends and sale proceeds from the SEI Investments Co shares. No individual client has an interest in more than 5% of the class, reflecting diversified beneficial ownership across multiple accounts.

Is Loomis Sayles seeking to influence control of SEI Investments Co (SEIC)?

Loomis, Sayles & Co., L.P. certifies the SEI Investments Co shares were acquired and are held in the ordinary course of business. It states they were not acquired and are not held to change or influence control of SEI Investments or in connection with such a transaction.