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seic-202601280000350894FALSE00003508942026-01-282026-01-28

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(D)

OF THE SECURITIES EXCHANGE ACT OF 1934

January 28, 2026 Date of report (Date of earliest event reported)

SEI INVESTMENTS COMPANY

(Exact name of registrant as specified in charter)

Pennsylvania 0-10200 23-1707341 (State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification No.)

1 Freedom Valley Drive Oaks, Pennsylvania 19456 (Address of Principal Executive Offices and Zip Code) (610) 676-1000 (Registrants’ Telephone Number, Including Area Code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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

Title of each classTrading SymbolName of each exchange on which registered Common Stock, par value $0.01 per shareSEICThe NASDAQ Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company ☐ 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. ☐

Item 2.02.    Results of Operations and Financial Condition. On Wednesday, January 28, 2026, SEI Investments Company (the "Company") issued a press release announcing its financial and operating results for the fourth quarter ended December 31, 2025. A copy of the press release is furnished as Exhibit 99.1 and incorporated in this Item 2.02 by reference. A recording of the earnings call referenced in the press release furnished as Exhibit 99.1 is available for replay on the Company’s website at ir.seic.com/events-presentations/events. As provided in General Instruction B.2 to Form 8-K, the information furnished in this Item 2.02 and Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, nor shall it be deemed incorporated by reference in any filing with the Securities and Exchange Commission, except as shall be expressly provided by specific reference in such filing.

Item 7.01.    Regulation FD Information. A copy of an earnings presentation that is intended to be used by representatives of the Company is furnished as Exhibit 99.2 to this Current Report on Form 8-K and is incorporated herein by reference. The information furnished pursuant to Item 7.01 and Exhibit 99.2 hereof shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, nor shall it be deemed incorporated by reference in any filing with the Securities and Exchange Commission, except as shall be expressly provided by specific reference in such filing.

Item 9.01.    Financial Statements and Exhibits.

Exhibit No.Description

99.1Press Release dated January 28, 2026 of SEI Investments Company related to the Company's financial and operating results for the fourth quarter ended December 31, 2025

99.2Earnings Presentation of SEI Investments Company for the fourth quarter ended December 31, 2025

104  Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

SEI INVESTMENTS COMPANY

Date:January 28, 2026By:/s/ Sean J. Denham Sean J. Denham Chief Financial and Chief Operating Officer

seic-202510220000350894FALSE00003508942025-10-222025-10-22

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(D)

OF THE SECURITIES EXCHANGE ACT OF 1934

October 22, 2025 Date of report (Date of earliest event reported)

SEI INVESTMENTS COMPANY

(Exact name of registrant as specified in charter)

Pennsylvania 0-10200 23-1707341 (State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification No.)

1 Freedom Valley Drive Oaks, Pennsylvania 19456 (Address of Principal Executive Offices and Zip Code) (610) 676-1000 (Registrants’ Telephone Number, Including Area Code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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

Title of each classTrading SymbolName of each exchange on which registered Common Stock, par value $0.01 per shareSEICThe NASDAQ Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company ☐ 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. ☐

Item 2.02.    Results of Operations and Financial Condition. On Wednesday, October 22, 2025, SEI Investments Company (the "Company") issued a press release announcing its financial and operating results for the third quarter ended September 30, 2025. A copy of the press release is furnished as Exhibit 99.1 and incorporated in this Item 2.02 by reference. A recording of the earnings call referenced in the press release furnished as Exhibit 99.1 is available for replay on the Company’s website at ir.seic.com/events-presentations/events. As provided in General Instruction B.2 to Form 8-K, the information furnished in this Item 2.02 and Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, nor shall it be deemed incorporated by reference in any filing with the Securities and Exchange Commission, except as shall be expressly provided by specific reference in such filing.

Item 7.01.    Regulation FD Information. A copy of an earnings presentation that is intended to be used by representatives of the Company is furnished as Exhibit 99.2 to this Current Report on Form 8-K and is incorporated herein by reference. The information furnished pursuant to Item 7.01 and Exhibit 99.2 hereof shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, nor shall it be deemed incorporated by reference in any filing with the Securities and Exchange Commission, except as shall be expressly provided by specific reference in such filing.

Item 9.01.    Financial Statements and Exhibits.

Exhibit No.Description

99.1Press Release dated October 22, 2025 of SEI Investments Company related to the Company's financial and operating results for the third quarter ended September 30, 2025

99.2Earnings Presentation of SEI Investments Company for the third quarter ended September 30, 2025

104  Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

SEI INVESTMENTS COMPANY

Date:October 22, 2025By:/s/ Sean J. Denham Sean J. Denham Chief Financial and Chief Operating Officer