X0306 4 2017-08-01 0001018399 ENTERPRISE BANCORP INC /MA/ EBTC 0001637827 GALLAGHER MICHAEL JOHN C/O ENTERPRISE BANCORP, INC. 222 MERRIMACK STREET LOWELL MA 01852 1 EVP-Principal Subsidiary Common Stock 2017-08-01 4 M 0 450 16.43 A 7277.4057 D Common Stock 2017-08-01 4 M 0 242 21.03 A 7519.4057 D Stock Option (Right to Buy) 16.43 2017-08-01 4 M 0 450 0 D 2017-03-19 2023-03-18 Common Stock 450 0 D Stock Option (Right to Buy) 21.03 2017-08-01 4 M 0 242 0 D 2019-03-17 2025-03-16 Common Stock 242 243 D Includes 1.5878 shares acquired through the Issuer's Employee Stock Purchase Plan on 6/7/17 Includes 17.8314 shares acquired through the Issuer's dividend reinvestment plan on June 1, 2017. /s/ Michael John Gallagher 2017-08-03