X0306 4 2015-03-17 0001018399 ENTERPRISE BANCORP INC /MA/ EBTC 0001515748 SILVA DIANE J C/O ENTERPRISE BANCORP, INC. 222 MERRIMACK STREET LOWELL MA 01852 1 EVP - Principal Subsidiary Common Stock 2015-03-17 4 A 0 808 0 A 64444.3732 D Option (Right to Buy) 21.03 2015-03-17 4 A 0 353 0 A 2025-03-16 Common Stock 353 353 D Options vest 50% on the second anniversary of the grant date and 50% on the fourth anniversary of the grant date. The first installment vests on March 17, 2017. /s/ George L. Duncan as attorney-in-fact for Diane J. Silva 2015-03-19