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

Date of Report (Date of earliest event reported): October 21, 2025

(Exact name of registrant as specified in its charter)

Delaware	001-13695	16-1213679
(State or other jurisdiction of incorporation)	(Commission File Number)	(IRS Employer Identification No.)

5790 Widewaters Parkway, DeWitt, New York	13214
(Address of principal executive offices)	(Zip Code)

Registrant’s telephone number, including area code: (315) 445-2282

Not applicable.

(Former name or former address, if changed since last report)

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 class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, $1.00 par value per share	CBU	New York Stock Exchange

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 October 21, 2025, Community Financial System, Inc. announced its results of operations for the third quarter ended September 30, 2025. The public announcement was made by means of a news release, the text of which is furnished as Exhibit 99.1.

The information in this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished under Item 2.02 and shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

Item 9.01

Financial Statements and Exhibits.

(d)  Exhibits

The following exhibit is being furnished pursuant to Item 2.02 above.

99.1

Press Release, dated October 21, 2025, issued by Community Financial System, Inc.

104

Cover Page Interactive Data File (embedded in the cover page formatted in Inline XBRL)

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.

	Community Financial System, Inc.


	By:	/s/ Marya Burgio Wlos
	Name: Marya Burgio Wlos
	Title: Executive Vice President and Chief Financial Officer

Dated: October 21, 2025

Exhibit Index

Exhibit Number	Description


99.1	Press Release, dated October 21, 2025, issued by Community Financial System, Inc.

104	Cover Page Interactive Data File (embedded in the cover page formatted in Inline XBRL)

COMMUNITY FINANCIAL SYSTEM, INC. 8-K