X0306 4 2017-12-12 0001018399 ENTERPRISE BANCORP INC /MA/ EBTC 0001282776 DUNCAN GEORGE L C/O ENTERPRISE BANCORP 222 MERRIMACK STREET LOWELL MA 01852 1 1 Chairman Common Stock 2017-12-12 4 S 0 100 34.11 D 394069 D Common Stock 2017-12-12 4 S 0 100 34.12 D 393969 D Common Stock 2017-12-12 4 S 0 100 34.29 D 393869 D Common Stock 2017-12-12 4 S 0 78 34.42 D 393791 D Common Stock 2017-12-12 4 S 0 100 34.48 D 393691 D Common Stock 2017-12-12 4 S 0 200 34.51 D 393491 D Common Stock 2017-12-12 4 S 0 100 34.52 D 393391 D Common Stock 2017-12-12 4 S 0 7 34.55 D 393384 D Common Stock 2017-12-12 4 S 0 50 34.61 D 393334 D Common Stock 2017-12-12 4 S 0 43 34.62 D 393291 D Common Stock 2017-12-12 4 S 0 22 34.64 D 393269 D Common Stock 2017-12-12 4 S 0 5 34.69 D 393264 D Common Stock 2017-12-13 4 S 0 200 34.15 D 393064 D Common Stock 2017-12-13 4 S 0 100 34.37 D 392964 D Common Stock 2017-12-13 4 S 0 100 34.38 D 392864 D Common Stock 2017-12-13 4 S 0 100 34.43 D 392764 D Common Stock 2017-12-13 4 S 0 300 34.48 D 392464 D Common Stock 2017-12-13 4 S 0 100 34.59 D 392364 D Common Stock 2017-12-13 4 S 0 100 34.80 D 392264 D Common Stock 2017-12-13 4 S 0 33 34.81 D 392231 D Common Stock 18445 I By Wife /s/ George L. Duncan 2017-12-14