UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13A-16 OR 15D-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of ~~December~~February, ~~2025~~2026

Commission File Number: 001-37877

The Bank of N.T. Butterfield & Son Limited

(Translation of registrant’s name into English)

65 Front Street

Hamilton, HM 12

Bermuda

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Form 20-F ý Form 40-F o

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): o

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): o

DOCUMENTS INCLUDED AS PART OF THIS FORM 6-K

Attached hereto (i) as Exhibit 99.1 is athe ~~press~~earnings release, ~~announcing~~(ii) aas ~~new~~Exhibit ~~share~~99.2 ~~repurchase~~is ~~program approved by~~ the ~~Board~~earnings ofcall ~~Directors~~presentation, ofall for The Bank of N.T. Butterfield & Son Limited for the three months and year ended December 31, 2025.

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, thereunto duly authorized.

Date: December 8, 2025	THE BANK OF N.T. BUTTERFIELD & SON LIMITED
Date: February 9, 2026	THE BANK OF N.T. BUTTERFIELD & SON LIMITED
	By:	/s/ Michael Schrum
	Name:	Michael Schrum
	Title:	President &and Group Chief Financial Officer


2

EXHIBIT INDEX

Exhibit						Description
99.1						~~Butterfield~~Earnings ~~Announces~~release ~~New~~- ~~Share~~Fourth ~~Repurchase~~quarter ~~Program~~and year-end 2025 results
99.2						Earnings call presentation - Fourth quarter and year-end 2025 results


3

Filing Compare · Bank of N.T. Butterfield & Son Ltd