COMMUNITY FINANCIAL SYSTEM, INC. — Director's Dealing 2018

May 3, 2018

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: COMMUNITY BANK SYSTEM, INC. (CBU)
CIK: 0000723188
Period of Report: 2018-05-02

Reporting Person: DONAHUE BRIAN D (EVP & Chief Banking Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2018-05-02	Common Stock	M	5087	$18.08	Acquired	44488	Direct
2018-05-02	Common Stock	S	5087	$57.7841	Disposed	39401	Direct
2018-05-03	Common Stock	M	62	$18.08	Acquired	39463	Direct
2018-05-03	Common Stock	S	62	$57.0342	Disposed	39401	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2018-05-02	Stock Option	$18.08	M	5087	Disposed	2019-01-29	Common Stock (5087)	Direct
2018-05-03	Stock Option	$18.08	M	62	Disposed	2019-01-29	Common Stock (62)	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	8496.4188	Indirect

Footnotes

F1: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $57.50 to $58.04, inclusive. The reporting person undertakes to provide Community Bank System, Inc., any security holder of Community Bank System, Inc. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

F2: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $57.01 to $57.04, inclusive. The reporting person undertakes to provide Community Bank System, Inc., any security holder of Community Bank System, Inc. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

F3: The option vests in five equal installments on January 29, 2010, 2011, 2012, 2013, and 2014.