X0303 4 2009-12-02 0 0001018399 ENTERPRISE BANCORP INC /MA/ EBTC 0001462721 Szablak Chester J JR C/O ENTERPRISE BANCORP, INC. 222 MERRIMACK STREET LOWELL MA 01852 0 1 0 0 EVP - Principal Subsidiary Common Stock 2009-12-02 4 P 0 1154 10.85 A 12073.9919 D Shares were acquired through the Issuer's supplemental community offering. Includes 4.5455 shares acquired through the Issuer's Employee Stock Purchase Plan on 4/27/09. Includes 2.1210 shares acquired through the Issuer's dividend reinvestment plan on 6/2/09. Includes 1.8414 shares acquired through the Issuer's dividend reinvestment plan on 9/2/09. /s/ Chester J. Szablak, Jr. 2009-12-03