Maureen Gillan-Myer (CBU) sells 3,450.3591 shares through 401(k) plan

Rhea-AI Filing Summary

COMMUNITY FINANCIAL SYSTEM, INC. executive Maureen A. Gillan-Myer, EVP and Chief Administrative & HR Officer, reported an indirect sale of 3,450.3591 shares of common stock on December 29, 2025 at an average price of $58.85 per share through a 401(k) plan.

After this activity, she reported 5,550 shares of common stock held in a direct ownership capacity, according to the Form 4 footnote and holding line.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Gillan-Myer Maureen A

(Last) (First) (Middle)

C/O COMMUNITY FINANCIAL SYSTEM, INC.

333 BUTTERNUT DRIVE

(Street)

SYRACUSE NY 13214

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
COMMUNITY FINANCIAL SYSTEM, INC. [ CBU ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP, Chief Admin & HR Officer

3. Date of Earliest Transaction (Month/Day/Year)
12/29/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	12/29/2025		S		3,450.3591	D	$58.85	0	I	By 401(k) Plan
Common Stock								5,550(1)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Represents common stock owned as of 12/29/2025.

	/s/ Danielle M. Cima, pursuant to a Confirming Statement executed by Maureen Gillan-Myer	03/04/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did CBU executive Maureen Gillan-Myer report?

Maureen A. Gillan-Myer reported an indirect sale of 3,450.3591 shares of COMMUNITY FINANCIAL SYSTEM common stock at $58.85 per share on December 29, 2025, executed through a 401(k) Plan account associated with her.

At what price were the CBU shares sold in Maureen Gillan-Myer’s Form 4 filing?

The reported sale of COMMUNITY FINANCIAL SYSTEM common stock was executed at an average price of $58.85 per share. This price applies to the 3,450.3591 shares sold indirectly through a 401(k) Plan on December 29, 2025.

How many CBU shares does Maureen Gillan-Myer report owning after the transaction?

Following the reported activity, Maureen A. Gillan-Myer shows 5,550 shares of COMMUNITY FINANCIAL SYSTEM common stock held directly. The Form 4 also indicates that her 401(k) Plan position involved the 3,450.3591 shares that were sold on December 29, 2025.

What role does Maureen Gillan-Myer hold at COMMUNITY FINANCIAL SYSTEM (CBU)?

Maureen A. Gillan-Myer is listed as an officer, serving as EVP, Chief Administrative & HR Officer of COMMUNITY FINANCIAL SYSTEM, INC. This officer status is disclosed in the Form 4 reporting her indirect stock sale on December 29, 2025.

Was the CBU stock sale by Maureen Gillan-Myer direct or through a plan account?

The sale was reported as indirect, with ownership noted as “By 401(k) Plan.” The 3,450.3591 shares of COMMUNITY FINANCIAL SYSTEM common stock were sold from this plan, while a separate line shows 5,550 shares held in direct ownership.

What does the footnote in Maureen Gillan-Myer’s CBU Form 4 indicate?

The footnote states that the entry represents common stock owned as of December 29, 2025. This clarifies that the reported holdings, including the directly owned 5,550 shares, are measured as of that specific date in the Form 4 disclosure.